CVE-2026-25539
moderate-risk
Published 2026-02-04
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.
Do I need to act?
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0.24% chance of exploitation
EPSS score — low exploit probability
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Not on CISA KEV list
No confirmed active exploitation reported to CISA
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Patch status unknown
Check vendor advisories for fix availability and mitigation guidance
9
CVSS 9.1/10
Critical
NETWORK
/ LOW complexity
Affected Products (1)
Affected Vendors
37
/ 100
moderate-risk
Severity
31/34 · Critical
Exploitability
1/34 · Minimal
Exposure
5/34 · Minimal