CVE-2026-25539

critical · 9.1

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.

9.1

CVSS

1.0%

EPSS (exploit prob.)

62nd

EPSS percentile

2026-02-04

Published

CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:C/C:H/I:H/A:H

Weaknesses

CWE-22

Affected products

Vendor	Product	Affected versions
b3log	siyuan	<= 3.5.3

Check a specific version with /api/v1/cve/match.

References

https://github.com/siyuan-note/siyuan/commit/d7f790755edf8c78d2b4176171e5a0cdcd720feb
https://github.com/siyuan-note/siyuan/security/advisories/GHSA-c4jr-5q7w-f6r9
https://github.com/siyuan-note/siyuan/security/advisories/GHSA-c4jr-5q7w-f6r9

Query this programmatically:

curl https://evil-db.io/api/v1/cve/CVE-2026-25539