{ "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-2026-33203", "tracking": { "current_release_date": "2026-03-29T16:14:32.346962Z", "generator": { "date": "2026-02-17T15:00:00Z", "engine": { "name": "V.E.L.M.A", "version": "1.7" } }, "id": "CVE-2026-33203", "initial_release_date": "2026-03-18T20:44:17.785953Z", "revision_history": [ { "date": "2026-03-18T20:44:17.785953Z", "number": "1", "summary": "CVE created.| Source created.| CVE status created. (valid)| Description created for source.| CVSS created.| References created (2).| CWES updated (1)." }, { "date": "2026-03-18T20:44:29.750842Z", "number": "2", "summary": "NCSC Score created." }, { "date": "2026-03-19T11:39:55.361064Z", "number": "3", "summary": "Source created.| CVE status created. (valid)| Description created for source.| CVSS created.| References created (2).| CWES updated (1)." }, { "date": "2026-03-20T23:25:37.256787Z", "number": "4", "summary": "Source created.| CVE status created. (valid)| Description created for source.| CVSS created.| References created (1).| CWES updated (1)." }, { "date": "2026-03-20T23:25:40.035030Z", "number": "5", "summary": "NCSC Score updated." }, { "date": "2026-03-20T23:39:01.284330Z", "number": "6", "summary": "Source created.| CVE status created. (valid)| Description created for source.| CVSS created.| Products connected (1).| References created (1).| CWES updated (1)." }, { "date": "2026-03-20T23:39:04.714575Z", "number": "7", "summary": "NCSC Score updated." }, { "date": "2026-03-21T15:23:09.448629Z", "number": "8", "summary": "Source connected.| CVE status created. (valid)| EPSS created." }, { "date": "2026-03-21T15:23:12.831624Z", "number": "9", "summary": "NCSC Score updated." }, { "date": "2026-03-24T07:48:20.185923Z", "number": "10", "summary": "Unknown change." }, { "date": "2026-03-24T07:48:22.176902Z", "number": "11", "summary": "NCSC Score updated." }, { "date": "2026-03-24T13:48:56.997483Z", "number": "12", "summary": "Products connected (1).| Product Identifiers created (1).| Exploits created (1)." }, { "date": "2026-03-24T13:49:08.119229Z", "number": "13", "summary": "NCSC Score updated." }, { "date": "2026-03-25T18:12:59.452647Z", "number": "14", "summary": "Source created.| CVE status created. (valid)| Description created for source.| CVSS created.| Products created (1).| References created (1).| CWES updated (1)." }, { "date": "2026-03-25T18:13:01.349367Z", "number": "15", "summary": "NCSC Score updated." }, { "date": "2026-03-25T18:13:28.931225Z", "number": "16", "summary": "Source created.| CVE status created. (valid)| Description created for source.| References created (1)." }, { "date": "2026-03-25T18:42:08.944718Z", "number": "17", "summary": "References created (1)." }, { "date": "2026-03-26T00:12:59.997986Z", "number": "18", "summary": "References created (1)." }, { "date": "2026-03-29T03:16:23.335602Z", "number": "19", "summary": "References removed (1)." }, { "date": "2026-03-29T03:16:25.623963Z", "number": "20", "summary": "NCSC Score updated." }, { "date": "2026-03-29T16:14:30.997681Z", "number": "21", "summary": "References created (1)." } ], "status": "interim", "version": "21" } }, "product_tree": { "branches": [ { "branches": [ { "branches": [ { "category": "product_version_range", "name": "vers:unknown/<3.6.2", "product": { "name": "vers:unknown/<3.6.2", "product_id": "CSAFPID-5899391", "product_identification_helper": { "cpe": "cpe:2.3:a:b3log:siyuan:*:*:*:*:*:*:*:*" } } } ], "category": "product_name", "name": "siyuan" } ], "category": "vendor", "name": "B3log" }, { "branches": [ { "branches": [ { "category": "product_version_range", "name": "vers:unknown/<3.6.2", "product": { "name": "vers:unknown/<3.6.2", "product_id": "CSAFPID-5878158" } }, { "category": "product_version_range", "name": "vers:unknown/>=0|<3.6.2", "product": { "name": "vers:unknown/>=0|<3.6.2", "product_id": "CSAFPID-5907207" } } ], "category": "product_name", "name": "siyuan" } ], "category": "vendor", "name": "siyuan-note" } ] }, "vulnerabilities": [ { "cve": "CVE-2026-33203", "cwe": { "id": "CWE-248", "name": "Uncaught Exception" }, "notes": [ { "category": "description", "text": "## Summary\nThe SiYuan kernel WebSocket server accepts unauthenticated connections when a specific “auth keepalive” query parameter is present. After connection, incoming messages are parsed using unchecked type assertions on attacker-controlled JSON.\n\nA remote attacker can send malformed messages that trigger a runtime panic, potentially crashing the kernel process and causing denial of service.\n\n## Details\n**1. Authentication Bypass via Keepalive Query**\n\nUnauthenticated connections are accepted if the request URI matches a specific pattern intended for an authentication page keepalive.\n\n**File: kernel/server/serve.go**\n\n```\nif !authOk {\n authOk = strings.Contains(s.Request.RequestURI, \"/ws?app=siyuan\") &&\n strings.Contains(s.Request.RequestURI, \"&id=auth&type=auth\")\n}\n\n```\n\n**2. Unsafe Type Assertions on Untrusted Input**\n\nIncoming JSON messages are parsed into a generic map and fields are accessed without validation.\n\n**File: kernel/server/serve.go**\n\n```\ncmdStr := request[\"cmd\"].(string)\ncmdId := request[\"reqId\"].(float64)\nparam := request[\"param\"].(map[string]interface{})\n\n```\nMalformed or missing fields trigger a runtime panic.\nThe handler does not implement local panic recovery, allowing crashes to propagate.\n\n## PoC\n**Step 1 — Prepare workspace directory**\n\n```sh\nmkdir -p ./workspace\n```\n\n**Step 2 — Run SiYuan container**\n\n```\ndocker run -d \\\n -p 6806:6806 \\\n -e SIYUAN_ACCESS_AUTH_CODE_BYPASS=true \\\n -v $(pwd)/workspace:/siyuan/workspace \\\n b3log/siyuan \\\n --workspace=/siyuan/workspace\n```\n\nService becomes reachable at http://127.0.0.1:6806\n\n**Step 3 — Confirm service availability**\n\nOpen in browser:\n\n```sh\nhttp://127.0.0.1:6806\n```\n\n**Step 4 — Connect to unauthenticated WebSocket endpoint**\n\n```sh\nws://127.0.0.1:6806/ws?app=siyuan&id=auth&type=auth\n```\n\nThis connection is accepted without credentials.\n\n**Step 5 — Send malformed payload**\n\nPayload:\n\n```sh\n\n{}\n\n```\n\n**Step 6 — Observe behavior**\n\nMonitor container logs:\n\n```sh\n\ndocker logs -f \n\n```\n## Impact\nAn unauthenticated attacker with network access can repeatedly crash the kernel, causing persistent denial of service.\n\nImpact is highest when the service is exposed beyond localhost (e.g., Docker deployments, reverse proxies, LAN access, or public hosting).", "title": "github - https://github.com/advisories/GHSA-3g9h-9hp4-654v" }, { "category": "description", "text": "## Summary\nThe SiYuan kernel WebSocket server accepts unauthenticated connections when a specific “auth keepalive” query parameter is present. After connection, incoming messages are parsed using unchecked type assertions on attacker-controlled JSON.\n\nA remote attacker can send malformed messages that trigger a runtime panic, potentially crashing the kernel process and causing denial of service.\n\n## Details\n**1. Authentication Bypass via Keepalive Query**\n\nUnauthenticated connections are accepted if the request URI matches a specific pattern intended for an authentication page keepalive.\n\n**File: kernel/server/serve.go**\n\n```\nif !authOk {\n authOk = strings.Contains(s.Request.RequestURI, \"/ws?app=siyuan\") &&\n strings.Contains(s.Request.RequestURI, \"&id=auth&type=auth\")\n}\n\n```\n\n**2. Unsafe Type Assertions on Untrusted Input**\n\nIncoming JSON messages are parsed into a generic map and fields are accessed without validation.\n\n**File: kernel/server/serve.go**\n\n```\ncmdStr := request[\"cmd\"].(string)\ncmdId := request[\"reqId\"].(float64)\nparam := request[\"param\"].(map[string]interface{})\n\n```\nMalformed or missing fields trigger a runtime panic.\nThe handler does not implement local panic recovery, allowing crashes to propagate.\n\n## PoC\n**Step 1 — Prepare workspace directory**\n\n```sh\nmkdir -p ./workspace\n```\n\n**Step 2 — Run SiYuan container**\n\n```\ndocker run -d \\\n -p 6806:6806 \\\n -e SIYUAN_ACCESS_AUTH_CODE_BYPASS=true \\\n -v $(pwd)/workspace:/siyuan/workspace \\\n b3log/siyuan \\\n --workspace=/siyuan/workspace\n```\n\nService becomes reachable at http://127.0.0.1:6806\n\n**Step 3 — Confirm service availability**\n\nOpen in browser:\n\n```sh\nhttp://127.0.0.1:6806\n```\n\n**Step 4 — Connect to unauthenticated WebSocket endpoint**\n\n```sh\nws://127.0.0.1:6806/ws?app=siyuan&id=auth&type=auth\n```\n\nThis connection is accepted without credentials.\n\n**Step 5 — Send malformed payload**\n\nPayload:\n\n```sh\n\n{}\n\n```\n\n**Step 6 — Observe behavior**\n\nMonitor container logs:\n\n```sh\n\ndocker logs -f \n\n```\n## Impact\nAn unauthenticated attacker with network access can repeatedly crash the kernel, causing persistent denial of service.\n\nImpact is highest when the service is exposed beyond localhost (e.g., Docker deployments, reverse proxies, LAN access, or public hosting).", "title": "github - https://api.github.com/advisories/GHSA-3g9h-9hp4-654v" }, { "category": "description", "text": "SiYuan is a personal knowledge management system. Prior to version 3.6.2, the SiYuan kernel WebSocket server accepts unauthenticated connections when a specific \"auth keepalive\" query parameter is present. After connection, incoming messages are parsed using unchecked type assertions on attacker-controlled JSON. A remote attacker can send malformed messages that trigger a runtime panic, potentially crashing the kernel process and causing denial of service. Version 3.6.2 fixes the issue.", "title": "nvd - https://services.nvd.nist.gov/rest/json/cves/2.0?cveId=CVE-2026-33203" }, { "category": "description", "text": "SiYuan is a personal knowledge management system. Prior to version 3.6.2, the SiYuan kernel WebSocket server accepts unauthenticated connections when a specific \"auth keepalive\" query parameter is present. After connection, incoming messages are parsed using unchecked type assertions on attacker-controlled JSON. A remote attacker can send malformed messages that trigger a runtime panic, potentially crashing the kernel process and causing denial of service. Version 3.6.2 fixes the issue.", "title": "cveprojectv5 - https://raw.githubusercontent.com/CVEProject/cvelistV5/main/cves/2026/33xxx/CVE-2026-33203.json" }, { "category": "description", "text": "## Summary\nThe SiYuan kernel WebSocket server accepts unauthenticated connections when a specific “auth keepalive” query parameter is present. After connection, incoming messages are parsed using unchecked type assertions on attacker-controlled JSON.\n\nA remote attacker can send malformed messages that trigger a runtime panic, potentially crashing the kernel process and causing denial of service.\n\n## Details\n**1. Authentication Bypass via Keepalive Query**\n\nUnauthenticated connections are accepted if the request URI matches a specific pattern intended for an authentication page keepalive.\n\n**File: kernel/server/serve.go**\n\n```\nif !authOk {\n authOk = strings.Contains(s.Request.RequestURI, \"/ws?app=siyuan\") &&\n strings.Contains(s.Request.RequestURI, \"&id=auth&type=auth\")\n}\n\n```\n\n**2. Unsafe Type Assertions on Untrusted Input**\n\nIncoming JSON messages are parsed into a generic map and fields are accessed without validation.\n\n**File: kernel/server/serve.go**\n\n```\ncmdStr := request[\"cmd\"].(string)\ncmdId := request[\"reqId\"].(float64)\nparam := request[\"param\"].(map[string]interface{})\n\n```\nMalformed or missing fields trigger a runtime panic.\nThe handler does not implement local panic recovery, allowing crashes to propagate.\n\n## PoC\n**Step 1 — Prepare workspace directory**\n\n```sh\nmkdir -p ./workspace\n```\n\n**Step 2 — Run SiYuan container**\n\n```\ndocker run -d \\\n -p 6806:6806 \\\n -e SIYUAN_ACCESS_AUTH_CODE_BYPASS=true \\\n -v $(pwd)/workspace:/siyuan/workspace \\\n b3log/siyuan \\\n --workspace=/siyuan/workspace\n```\n\nService becomes reachable at http://127.0.0.1:6806\n\n**Step 3 — Confirm service availability**\n\nOpen in browser:\n\n```sh\nhttp://127.0.0.1:6806\n```\n\n**Step 4 — Connect to unauthenticated WebSocket endpoint**\n\n```sh\nws://127.0.0.1:6806/ws?app=siyuan&id=auth&type=auth\n```\n\nThis connection is accepted without credentials.\n\n**Step 5 — Send malformed payload**\n\nPayload:\n\n```sh\n\n{}\n\n```\n\n**Step 6 — Observe behavior**\n\nMonitor container logs:\n\n```sh\n\ndocker logs -f \n\n```\n## Impact\nAn unauthenticated attacker with network access can repeatedly crash the kernel, causing persistent denial of service.\n\nImpact is highest when the service is exposed beyond localhost (e.g., Docker deployments, reverse proxies, LAN access, or public hosting).", "title": "osv - https://www.googleapis.com/download/storage/v1/b/osv-vulnerabilities/o/Go%2FGHSA-3g9h-9hp4-654v.json?alt=media" }, { "category": "description", "text": "SiYuan has an Unauthenticated WebSocket DoS via Auth Keepalive Bypass in github.com/siyuan-note/siyuan/kernel.\n\nNOTE: The source advisory for this report contains additional versions that could not be automatically mapped to standard Go module versions.\n\n(If this is causing false-positive reports from vulnerability scanners, please suggest an edit to the report.)\n\nThe additional affected modules and versions are: github.com/siyuan-note/siyuan/kernel before v3.6.2.", "title": "osv - https://www.googleapis.com/download/storage/v1/b/osv-vulnerabilities/o/Go%2FGO-2026-4752.json?alt=media" }, { "category": "other", "text": "0.001", "title": "EPSS" }, { "category": "other", "text": "3.4", "title": "NCSC Score" }, { "category": "other", "text": "There is exploit data available from source Nvd, Is related to (a version of) an uncommon product", "title": "NCSC Score top decreasing factors" } ], "product_status": { "known_affected": [ "CSAFPID-5878158", "CSAFPID-5899391", "CSAFPID-5907207" ] }, "references": [ { "category": "external", "summary": "Source - github", "url": "https://github.com/advisories/GHSA-3g9h-9hp4-654v" }, { "category": "external", "summary": "Source raw - github", "url": "https://api.github.com/advisories/GHSA-3g9h-9hp4-654v" }, { "category": "external", "summary": "Source - github", "url": "https://api.github.com/advisories/GHSA-3g9h-9hp4-654v" }, { "category": "external", "summary": "Source - nvd", "url": "https://services.nvd.nist.gov/rest/json/cves/2.0?cveId=CVE-2026-33203" }, { "category": "external", "summary": "Source - cveprojectv5", "url": "https://raw.githubusercontent.com/CVEProject/cvelistV5/main/cves/2026/33xxx/CVE-2026-33203.json" }, { "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%2FGHSA-3g9h-9hp4-654v.json?alt=media" }, { "category": "external", "summary": "Source - osv", "url": "https://www.googleapis.com/download/storage/v1/b/osv-vulnerabilities/o/Go%2FGO-2026-4752.json?alt=media" }, { "category": "external", "summary": "Reference - cveprojectv5; github; nvd; osv", "url": "https://github.com/siyuan-note/siyuan/security/advisories/GHSA-3g9h-9hp4-654v" }, { "category": "external", "summary": "Reference - github", "url": "https://github.com/advisories/GHSA-3g9h-9hp4-654v" }, { "category": "external", "summary": "Reference - github; osv", "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-33203" } ], "scores": [ { "cvss_v3": { "version": "3.1", "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H", "baseScore": 7.5, "baseSeverity": "HIGH" }, "products": [ "CSAFPID-5878158", "CSAFPID-5899391", "CSAFPID-5907207" ] } ], "title": "CVE-2026-33203" } ] }