Path Traversal in Siyuan-Note Siyuan
CVE-2026-85580
SiYuan versions before v3.8.2 contain a path guard bypass vulnerability in the MCP file-access handler that uses case-sensitive matching on Linux filesystems. Attackers can read the protected publishAccess.json file by requesting case-variant paths like PublishAccess.json to disclose sensitive publish-access configuration and metadata.
Vulnerability class: Path Traversal (Directory Traversal)
Published · last modified .
CVSS v3 metric
CVSS v3 base score 6.5 (Medium). Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N.
EPSS exploit prediction
EPSS: 0.006 (46.5th percentile), scored .
Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 47th percentile — 46.5% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.
EPSS over last 30 days · oldest: 0.005 · newest: 0.006 · change: +0.001
Affected products
Weakness classification (CWE)
References
- github.com/siyuan-note/siyuan/security/advisories/GHSA-mmgw-3mx9-cfwp (vendor-advisory)
- www.vulncheck.com/advisories/siyuan-before-3.8.2-path-guard-bypass-via-case-mis… (third-party-advisory)
Frequently asked questions
- What is CVE-2026-85580?
- CVE-2026-85580 is a medium-severity vulnerability in Siyuan-Note Siyuan, classified under Path Traversal. CVSS score: 6.5/10. Published 2026-09-04.
- How severe is CVE-2026-85580?
- Medium severity. CVSS v3 base score is 6.5 out of 10.