CVE-2026-25539

Name: CVE-2026-25539
Creator: NVD / NIST
Published: 2026-02-04T22:16:00.083+00:00
License: https://creativecommons.org/publicdomain/zero/1.0/

HIGHCVSS 7.2/10EPSS 1.02%

Last modified Jun 17, 2026

CVE-2026-25539 is a high-severity vulnerability rated 7.2/10 on the CVSS scale. 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. EPSS estimates a 1.02% chance of exploitation in the next 30 days.

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.

Metrics

CVSS 3.1

7.2/10

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

EPSS Probability

1.02%

58.9th percentile

Probability of exploitation in the next 30 days. Learn more

Weakness Enumeration

CWE-22

Affected Software

Vendor	Product	Versions
B3log	Siyuan	<= 3.5.3

References

https://github.com/siyuan-note/siyuan/commit/d7f790755edf8c78d2b4176171e5a0cdcd720febPatch
https://github.com/siyuan-note/siyuan/security/advisories/GHSA-c4jr-5q7w-f6r9Exploit, Vendor Advisory
https://github.com/siyuan-note/siyuan/security/advisories/GHSA-c4jr-5q7w-f6r9Exploit, Vendor Advisory

Timeline

Published: Feb 4, 2026
Last Modified: Jun 17, 2026
Status: Analyzed

Frequently Asked Questions

What is CVE-2026-25539?

How severe is CVE-2026-25539?

CVE-2026-25539 has a CVSS score of 7.2/10 (HIGH severity). The EPSS model estimates a 1.02% probability of exploitation in the next 30 days.

How do I fix CVE-2026-25539?

Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.

Are you affected by CVE-2026-25539?

Run a free Strix scan to check your systems for this vulnerability.

Scan your code now

Source: NVD / NIST