CVE-2026-126776
SiYuan 3.7.0 before 3.8.10 Path Traversal File Write via MCP web_fetch
CVSS Score
5.3
EPSS Score
0.0%
EPSS Percentile
0th
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.
| CWE | CWE-22 |
| Vendor | siyuan-note |
| Product | siyuan |
| Published | Nov 11, 2026 |
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CVSS v3 Breakdown
CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:N/I:H/A:N Attack Vector
Network
Attack Complexity
High
Privileges Required
None
User Interaction
Required
Scope
Unchanged
Confidentiality
None
Integrity
High
Availability
None
Affected Versions
siyuan-note / siyuan
3.7.0 < 3.8.10
References
github.com: https://github.com/siyuan-note/siyuan/security/advisories/GHSA-hq2c-hh95-vrr6 github.com: https://github.com/siyuan-note/siyuan/commit/94d6a42a0362c0a6938a29ab84addb1fe0aca21c github.com: https://github.com/siyuan-note/siyuan/releases/tag/v3.8.10 github.com: https://github.com/siyuan-note/siyuan/blob/v3.7.0/kernel/util/webfetch.go#L155 vulncheck.com: https://www.vulncheck.com/advisories/siyuan-3.7.0-before-3.8.10-path-traversal-file-write-via-mcp-web-fetch
Credits
Zachariah Mithani (AploSec)