High severity · published Sep 26, 2026
CVE-2026-100637
SiYuan before v3.8.4 Path Traversal via checkoutRepo sessionID
7.6
CVSS
0.6%
EPSS
No
On KEV
Description
SiYuan versions before v3.8.4 contain a path traversal vulnerability in the checkoutRepo endpoint that allows authenticated administrators to write JSON files outside the workspace. Attackers can supply a sessionID parameter containing directory traversal sequences to overwrite arbitrary JSON files in pre-existing kernel-writable directories outside workspace boundaries.
CVSS vector
CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:C/C:N/I:H/A:L
Attack vector
Network
Complexity
Low
Privileges
High
User interaction
None
Confidentiality
None
Integrity
High
Availability
Low
Scope
Changed
Exploitation
Is it being used?
Exploit prediction (EPSS)0.6% · higher than 46% of CVEs
Exploited in the wildNo evidence yet
CISA KEVNot listed
Ransomware campaign useNot known
Affected products
Which versions
SI
siyuan · siyuan-note
before 3.8.4 · source: vendor
References
NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-100637
CVE.org
https://www.cve.org/CVERecord?id=CVE-2026-100637
vendor-advisory
https://github.com/siyuan-note/siyuan/security/advisories/GHSA-jhmh-hr4g-c5g2
third-party-advisory
https://www.vulncheck.com/advisories/siyuan-before-3.8.4-path-traversal-via-checkoutrepo-sessionid
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