CVE-2026-23852: b3log siyuan Code Injection

Vulnerability summary

CVE-2026-23852 is a critical (CVSS 9.6) Code Injection vulnerability in b3log siyuan. EPSS estimates a 0.81% chance of exploitation in the next 30 days, higher than 56.2% of scored vulnerabilities. 1 public exploit is recorded.

Timeline

1. 19-01-2026
   PublishedVulnerability first disclosed.
2. 20-01-2026
   Last modifiedVulnerability information updated.

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.

• CWE-94Improper Control of Generation of Code ('Code Injection')The product constructs all or part of a code segment using externally-influenced input from an upstream component, but it does not neutralize or incorrectly neutralizes special elements that could modify the syntax or behavior of the intended code segment.
• CWE-79Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')The product does not neutralize or incorrectly neutralizes user-controllable input before it is placed in output that is used as a web page that is served to other users.