CVE-2026-25539
Critical
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.
SeverityCritical
CVSS9.1
Exploit probability—
ProductB3log Siyuan
PublishedFeb 4, 2026
First seenFeb 4, 2026
Weakness typeCWE-22Path traversal
How to fix
Sources list no fixed version or patch link for this vulnerability.
Affected products
| Product | Affected versions | Fixed in |
|---|---|---|
| b3log siyuan | v ≤ 3.5.3 | — |
| github.com/siyuan-note/siyuan/kernelGo | v ≤ 0.0.0-20260126094835-d5d10dd41b0c, No range specified | — |
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