CVE-2026-126776
SiYuan 3.7.0 before 3.8.10 Path Traversal File Write via MCP web_fetch
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.
Fixes and workarounds
Fix
The reporting source identifies this reference as a patch. Check the advisory for affected versions and supported release branches.
Source: CNA: VulnCheckAffected products and versions
| Product | Versions | Authority |
|---|---|---|
| siyuan siyuan-note github.com/siyuan-note/siyuan/kernel
golang |
≥ 3.7.0; < 3.8.10 (affected, semver) 3.8.10 (unaffected, semver) Other versions: unaffected |
CNA: VulnCheck |
Version ranges are source assertions. Check the vendor advisory and your installed configuration before determining exposure.
CVSS assessments
| Version / score | Vector | Authority |
|---|---|---|
| 4.0 / 6.0 medium |
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: VulnCheck |
| 3.1 / 5.3 medium |
CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:N/I:H/A:N | CNA: VulnCheck |
Exploit evidence
No exploit evidence in collected sources. This is not proof of no exploitation.
References
- https://github.com/siyuan-note/siyuan/security/advisories/GHSA-hq2c-hh95-vrr6CNA: VulnCheck · vendor-advisory
- https://github.com/siyuan-note/siyuan/commit/94d6a42a0362c0a6938a29ab84addb1fe0aca21cCNA: VulnCheck · patch
- https://github.com/siyuan-note/siyuan/releases/tag/v3.8.10CNA: VulnCheck · release-notes
- https://github.com/siyuan-note/siyuan/blob/v3.7.0/kernel/util/webfetch.go#L155CNA: VulnCheck · technical-description
- https://www.vulncheck.com/advisories/siyuan-3.7.0-before-3.8.10-path-traversal-file-write-via-mcp-web-fetchCNA: VulnCheck · third-party-advisory
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