Vulnerability Description
SiYuan is a personal knowledge management system. Prior to version 3.5.5, the /api/file/copyFile endpoint does not validate the dest parameter, allowing authenticated users to write files to arbitrary locations on the filesystem. This can lead to Remote Code Execution (RCE) by writing to sensitive locations such as cron jobs, SSH authorized_keys, or shell configuration files. This issue has been patched in version 3.5.5.
CVSS Score
CRITICAL
Affected Products
| Vendor | Product | Versions |
|---|---|---|
| B3Log | Siyuan | <= 3.5.3 |
Related Weaknesses (CWE)
References
- https://github.com/siyuan-note/siyuan/commit/d7f790755edf8c78d2b4176171e5a0cdcd7Patch
- https://github.com/siyuan-note/siyuan/security/advisories/GHSA-c4jr-5q7w-f6r9ExploitVendor Advisory
- https://github.com/siyuan-note/siyuan/security/advisories/GHSA-c4jr-5q7w-f6r9ExploitVendor Advisory
FAQ
What is CVE-2026-25539?
CVE-2026-25539 is a vulnerability with a CVSS score of 9.1 (CRITICAL). SiYuan is a personal knowledge management system. Prior to version 3.5.5, the /api/file/copyFile endpoint does not validate the dest parameter, allowing authenticated users to write files to arbitrary...
How severe is CVE-2026-25539?
CVE-2026-25539 has been rated CRITICAL with a CVSS base score of 9.1/10. This is considered a critical vulnerability requiring immediate attention.
Is there a patch for CVE-2026-25539?
Check the references section above for vendor advisories and patch information. Affected products include: B3Log Siyuan.