CVE-2026-23852

Critical

Description

SiYuan is a personal knowledge management system. Versions prior to 3.5.4 have a stored Cross-Site Scripting (XSS) vulnerability that allows an attacker to inject arbitrary HTML attributes into the `icon` attribute of a block via the `/api/attr/setBlockAttrs` API. The payload is later rendered in the dynamic icon feature in an unsanitized context, leading to stored XSS and, in the desktop environment, potential remote code execution (RCE). This issue bypasses the previous fix for issue `#15970` (XSS → RCE via dynamic icons). Version 3.5.4 contains an updated fix.

SeverityCritical
CVSS9.6
Exploit probability—
ProductB3log Siyuan
PublishedJan 19, 2026
First seenJan 19, 2026

How to fix

Update
  • b3log siyuan3.5.4 or later

Affected products

ProductAffected versionsFixed in
b3log siyuanv < 3.5.43.5.4

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