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Critical · 9.1 CVE-2026-25539 EUVD-2026-5331GHSA-c4jr-5q7w-f6r9GO-2026-4387

SiYuan has Arbitrary File Write via /api/file/copyFile leading to RCE

Published Feb 4, 2026 · Updated Feb 5, 2026 · Assigned by GitHub_M

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.

Affected products

VendorProductAffectedFixed
siyuan-note siyuan < 3.5.5 —

Affected packages

EcosystemPackageAffectedFixedRecord
Go github.com/siyuan-note/siyuan/kernel <= 0.0.0-20260126094835-d5d10dd41b0c — GHSA-c4jr-5q7w-f6r9
Go github.com/siyuan-note/siyuan/kernel all versions — GO-2026-4387

References