CVE-2026-126776 json
SiYuan 3.7.0 before 3.8.10 Path Traversal File Write via MCP web_fetch
published 11d ago modified 15h ago also EUVD-2026-123770 , GHSA-hq2c-hh95-vrr6
Unreviewed: the maintainers' own advisory
Published by the maintainers on their GitHub repository siyuan-note/siyuan. GitHub has not reviewed it into the GitHub Advisory Database, so the affected packages and versions are the maintainers' word. Read the full advisory on GitHub.
- cvss
- 5.3
- version 3.1, CNA
- cisa kev
- Not listed
- not in CISA's catalog
- epss
- —
- no EPSS score yet
- public exploits
- 0
- none known
Summary
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.
Patch / fix
- siyuan-note siyuan 3.8.10
Is CVE-2026-126776 in your stack? Fencer shows which of your repositories are affected as soon as an advisory lands, and opens the fix as a pull request.
Check with FencerCVSS scores
| assigned by | version | score | vector |
|---|---|---|---|
| CNA | 4.0 | 6.0 | 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 |
| CNA | 3.1 | 5.3 | CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:N/I:H/A:N |
| CNA | 4.0 | 6.0 | 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 |
| NVD | 3.1 | 5.3 | CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:N/I:H/A:N |
Affected products
- siyuan-note siyuan
Classification
- Weakness
-
- CWE-22 Improper Limitation of a Pathname to a Restricted Directory
References
-
github.com
/siyuan-note/siyuan/commit/94d6a42a0362c0a6938a29ab84addb1fe0aca21c
patch
-
github.com
/siyuan-note/siyuan/security/advisories/GHSA-hq2c-hh95-vrr6
vendor-advisory, advisory
-
github.com
/siyuan-note/siyuan/releases/tag/v3.8.10
release-notes
-
github.com
/siyuan-note/siyuan/blob/v3.7.0/kernel/util/webfetch.go#L155
technical-description
-
vulncheck.com
/advisories/siyuan-3.7.0-before-3.8.10-path-traversal-file-write-via-mcp-web-fetch
third-party-advisory
Sources
- CVE List CVE-2026-126776
- NVD CVE-2026-126776
- Maintainer advisory GHSA-hq2c-hh95-vrr6
Fencer Intel keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.
The maintainers of siyuan-note/siyuan published their own advisory on GitHub. Reviewed sources take precedence over it.