Medium severity · published Sep 4, 2026
CVE-2026-85580
SiYuan before v3.8.2 Path Guard Bypass via Case Mismatch
6.5
CVSS
0.6%
EPSS
No
On KEV
Description
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.
CVSS vector
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N
Attack vector
Network
Complexity
Low
Privileges
Low
User interaction
None
Confidentiality
High
Integrity
None
Availability
None
Scope
Unchanged
Exploitation
Is it being used?
Exploit prediction (EPSS)0.6% · higher than 47% of CVEs
Exploited in the wildNo evidence yet
CISA KEVNot listed
Ransomware campaign useNot known
Affected products
Which versions
SI
siyuan · siyuan-note
before 3.8.2 · source: vendor
References
NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-85580
CVE.org
https://www.cve.org/CVERecord?id=CVE-2026-85580
github.com
https://github.com/siyuan-note/siyuan/security/advisories/GHSA-mmgw-3mx9-cfwp
www.vulncheck.com
https://www.vulncheck.com/advisories/siyuan-before-3.8.2-path-guard-bypass-via-case-mismatch
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