{"id":"CVE-2026-126776","aliases":["EUVD-2026-123770","GHSA-fgx6-mcm3-mrhr","GHSA-hq2c-hh95-vrr6"],"status":"published","title":"SiYuan 3.7.0 before 3.8.10 Path Traversal File Write via MCP web_fetch","description":"SiYuan 3.7.0 before 3.8.10 on Windows contains a path traversal vulnerability in kernel/util/webfetch.go that allows attackers to write files outside the import directory via backslash-encoded filenames. Attackers controlling a URL fetched by the MCP web_fetch or http_request tools can use %5C-encoded ..\\ sequences to write chosen response bytes to directories above temp/import that are writable by the SiYuan user.","severity":{"version":"4.0","score":6,"vector":"CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:P/VC:N/VI:H/VA:N/SC:N/SI:N/SA:N","level":"medium","assessor":"cna","from":"cve"},"epss":{"day":"2026-11-12","score":0.00349,"percentile":0.28931,"model":"v2026.06.15"},"facts":{"in_kev":false,"known_exploited":false,"public_exploit":false,"fix_available":false},"cwes":["CWE-22"],"published":"2026-11-11T18:41:08Z","modified":"2026-11-12T10:45:30Z","products":[{"vendor":"siyuan-note","product":"siyuan"}],"references":[{"url":"https://github.com/siyuan-note/siyuan/security/advisories/GHSA-hq2c-hh95-vrr6","tags":["vendor-advisory","advisory"]},{"url":"https://github.com/siyuan-note/siyuan/commit/94d6a42a0362c0a6938a29ab84addb1fe0aca21c","tags":["patch","fix"]},{"url":"https://github.com/siyuan-note/siyuan/releases/tag/v3.8.10","tags":["release-notes","advisory"]},{"url":"https://github.com/siyuan-note/siyuan/blob/v3.7.0/kernel/util/webfetch.go#L155","tags":["technical-description","article"]},{"url":"https://www.vulncheck.com/advisories/siyuan-3.7.0-before-3.8.10-path-traversal-file-write-via-mcp-web-fetch","tags":["third-party-advisory","advisory"]},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-126776","tags":["advisory"]},{"url":"https://github.com/advisories/GHSA-fgx6-mcm3-mrhr"},{"url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/126xxx/CVE-2026-126776.json","tags":["advisory"]},{"url":"https://github.com/siyuan-note/siyuan","tags":["package"]}],"sources":{"cve":[{"id":"CVE-2026-126776","title":"SiYuan 3.7.0 before 3.8.10 Path Traversal File Write via MCP web_fetch","description":"SiYuan 3.7.0 before 3.8.10 on Windows contains a path traversal vulnerability in kernel/util/webfetch.go that allows attackers to write files outside the import directory via backslash-encoded filenames. Attackers controlling a URL fetched by the MCP web_fetch or http_request tools can use %5C-encoded ..\\ sequences to write chosen response bytes to directories above temp/import that are writable by the SiYuan user.","status":"published","published":"2026-11-11T18:41:08.401Z","modified":"2026-11-12T17:55:58.8Z","cvss":[{"version":"4.0","score":6,"vector":"CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:P/VC:N/VI:H/VA:N/SC:N/SI:N/SA:N","level":"medium","assessor":"cna"},{"version":"3.1","score":5.3,"vector":"CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:N/I:H/A:N","level":"medium","assessor":"cna"}],"cwes":["CWE-22"],"updated_at":"2026-11-11T19:31:49.923897Z"}],"euvd":[{"id":"EUVD-2026-123770","description":"SiYuan 3.7.0 before 3.8.10 on Windows contains a path traversal vulnerability in kernel/util/webfetch.go that allows attackers to write files outside the import directory via backslash-encoded filenames. Attackers controlling a URL fetched by the MCP web_fetch or http_request tools can use %5C-encoded ..\\ sequences to write chosen response bytes to directories above temp/import that are writable by the SiYuan user.","status":"published","published":"2026-11-11T18:41:08Z","modified":"2026-11-12T17:55:58Z","cvss":[{"version":"4.0","score":6,"vector":"CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:P/VC:N/VI:H/VA:N/SC:N/SI:N/SA:N","level":"medium"}],"updated_at":"2026-11-11T23:30:57.784734Z"}],"ghsa":[{"id":"GHSA-fgx6-mcm3-mrhr","title":"SiYuan 3.7.0 before 3.8.10 on Windows contains a path traversal vulnerability in kernel/util...","description":"SiYuan 3.7.0 before 3.8.10 on Windows contains a path traversal vulnerability in kernel/util/webfetch.go that allows attackers to write files outside the import directory via backslash-encoded filenames. Attackers controlling a URL fetched by the MCP web_fetch or http_request tools can use %5C-encoded ..\\ sequences to write chosen response bytes to directories above temp/import that are writable by the SiYuan user.","status":"published","published":"2026-11-11T21:32:57Z","modified":"2026-11-11T21:33:08Z","cvss":[{"version":"4.0","score":6,"vector":"CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:P/VC:N/VI:H/VA:N/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X","level":"medium"},{"version":"3.1","score":5.3,"vector":"CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:N/I:H/A:N","level":"medium"}],"cwes":["CWE-22"],"updated_at":"2026-11-11T21:36:27.876473Z"}],"nvd":[{"id":"CVE-2026-126776","description":"SiYuan 3.7.0 before 3.8.10 on Windows contains a path traversal vulnerability in kernel/util/webfetch.go that allows attackers to write files outside the import directory via backslash-encoded filenames. Attackers controlling a URL fetched by the MCP web_fetch or http_request tools can use %5C-encoded ..\\ sequences to write chosen response bytes to directories above temp/import that are writable by the SiYuan user.","status":"published","published":"2026-11-11T19:17:38.287Z","modified":"2026-11-12T18:17:27.487Z","cvss":[{"version":"4.0","score":6,"vector":"CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:P/VC:N/VI:H/VA:N/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X","level":"medium","assessor":"secondary"},{"version":"3.1","score":5.3,"vector":"CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:N/I:H/A:N","level":"medium","assessor":"secondary"}],"cwes":["CWE-22"],"updated_at":"2026-11-12T19:32:19.423888Z"}],"osv":[{"id":"CVE-2026-126776","title":"SiYuan 3.7.0 before 3.8.10 Path Traversal File Write via MCP web_fetch","description":"SiYuan 3.7.0 before 3.8.10 on Windows contains a path traversal vulnerability in kernel/util/webfetch.go that allows attackers to write files outside the import directory via backslash-encoded filenames. Attackers controlling a URL fetched by the MCP web_fetch or http_request tools can use %5C-encoded ..\\ sequences to write chosen response bytes to directories above temp/import that are writable by the SiYuan user.","status":"published","published":"2026-11-11T18:41:08.401Z","modified":"2026-11-13T02:47:26.652818608Z","cvss":[{"version":"4.0","score":6,"vector":"CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:P/VC:N/VI:H/VA:N/SC:N/SI:N/SA:N","level":"medium"}],"cwes":["CWE-22"],"updated_at":"2026-11-13T02:57:32.2543Z"}]}}