Is CVE-2026-25539 in the CISA KEV catalog?

No. CVE-2026-25539 is not currently on the CISA Known Exploited Vulnerabilities list.

What is the CVSS severity of CVE-2026-25539?

CVE-2026-25539 has a CVSS v3 base score of 9.1 (CRITICAL).

What is the EPSS score for CVE-2026-25539?

CVE-2026-25539 has an EPSS score of 1.02% (59th percentile), estimating the probability of exploitation in the next 30 days.

CVE & CISA-KEV Catalog

CVE-2026-25539

CRITICAL

9.1

CVSS v3

NVD

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.

CWE-22Path Traversal

CVSS v3 Vector

Exploitability

Attack VectorNetwork

Attack ComplexityLow

Privileges RequiredHigh

User InteractionNone

ScopeChanged

Impact

ConfidentialityHigh

IntegrityHigh

AvailabilityHigh

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

Exploit Intelligence

1.02%probability of exploitation in 30 days

59thpercentile

Moderate risk: more likely to be exploited than 59% of all known CVEs.

References

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This product uses NVD data but is not endorsed or certified by the NVD. EPSS scores courtesy of FIRST.org (https://www.first.org/epss). Source: CISA KEV Catalog. Data as of 2026-02-11.