CVE-2026-23852

CRITICAL

SiYuan <3.5.4 - XSS

Title source: llm
STIX 2.1

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.

References (2)

Core 2

Scores

CVSS v3 9.6
EPSS 0.0019
EPSS Percentile 40.8%
Attack Vector NETWORK
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:H/A:H

CISA SSVC

Vulnrichment
Exploitation none
Automatable yes
Technical Impact partial

Details

CWE
CWE-79 CWE-94
Status published
Products (1)
b3log/siyuan < 3.5.4
Published Jan 19, 2026
Tracked Since Feb 18, 2026