CVE-2026-25539

CRITICAL
2026-02-04 [email protected] GHSA-c4jr-5q7w-f6r9
9.1
CVSS 3.1
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CVSS Vector

CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:C/C:H/I:H/A:H
Attack Vector
Network
Attack Complexity
Low
Privileges Required
High
User Interaction
None
Scope
Changed
Confidentiality
High
Integrity
High
Availability
High

Lifecycle Timeline

4
Analysis Generated
Mar 12, 2026 - 21:54 vuln.today
PoC Detected
Feb 11, 2026 - 19:10 vuln.today
Public exploit code
Patch Released
Feb 11, 2026 - 19:10 nvd
Patch available
CVE Published
Feb 04, 2026 - 22:16 nvd
CRITICAL 9.1

Tags

Ssh RCE Siyuan

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.

Analysis

SiYuan knowledge management system prior to 3.5.5 has a path traversal in /api/file/copyFile allowing arbitrary file operations on the server.

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Remediation

Within 24 hours: Identify all systems running SiYuan and their versions; restrict network access to SiYuan instances to trusted users only. Within 7 days: Upgrade all SiYuan installations to version 3.5.5 or later; validate successful patching across all instances. …

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Priority Score

66
Low Medium High Critical
KEV: 0
EPSS: +0.6
CVSS: +46
POC: +20

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CVE-2026-25539 vulnerability details – vuln.today
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