CVE-2026-23852: SiYuan vulnerable to Stored XSS / RCE via `setBlockAttrs` icon attribute

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.

CVSS vector

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

Attack vector

Network

Complexity

Low

Privileges

None

User interaction

Required

Confidentiality

High

Integrity

High

Availability

High

Scope

Changed

Exploitation

Is it being used?

Exploit prediction (EPSS)0.8% · higher than 57% of CVEs

Exploited in the wildNo evidence yet

CISA KEVNot listed

Ransomware campaign useNot known

Affected products

Which versions

SI

siyuan · siyuan-note

< 3.5.4 · source: vendor, NVD