What is CVE-2026-25539?

CVE-2026-25539 is a critical-severity vulnerability in Siyuan-note Siyuan, classified under Path Traversal. CVSS score: 9.1/10. Published 2026-02-04.

How severe is CVE-2026-25539?

Critical severity. CVSS v3 base score is 9.1 out of 10.

Path Traversal in Siyuan-note Siyuan

CVE-2026-25539

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…

Vulnerability class: Path Traversal (Directory Traversal)

EPSS: 0.002 (47.6th percentile) — read the EPSS interpretation.

CVSS v3 metric

CVSS v3 base score 9.1 (Critical). Vector: CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:C/C:H/I:H/A:H.

Affected products

Siyuan-note Siyuan — versions < 3.5.5

Weakness classification (CWE)

CWE-22 — Path Traversal

References

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

Frequently asked questions

What is CVE-2026-25539?: CVE-2026-25539 is a critical-severity vulnerability in Siyuan-note Siyuan, classified under Path Traversal. CVSS score: 9.1/10. Published 2026-02-04.
How severe is CVE-2026-25539?: Critical severity. CVSS v3 base score is 9.1 out of 10.