CVE-2026-40922: b3log siyuan Cross-site Scripting

Vulnerability summary

CVE-2026-40922 is a medium (CVSS 5.4) Cross-site Scripting vulnerability in b3log siyuan. EPSS estimates a 0.38% chance of exploitation in the next 30 days, higher than 30.1% of scored vulnerabilities. 1 public exploit is recorded.

Timeline

1. 16-04-2026
   PublishedVulnerability first disclosed.
2. 20-04-2026
   Last modifiedVulnerability information updated.

Description

SiYuan is an open-source personal knowledge management system. In versions 3.6.1 through 3.6.3, a prior fix for XSS in bazaar README rendering (incomplete fix for CVE-2026-33066) enabled the Lute HTML sanitizer, but the sanitizer does not block iframe tags, and its URL-prefix blocklist does not effectively filter srcdoc attributes which contain raw HTML rather than URLs. A malicious bazaar package author can include an iframe with a srcdoc attribute containing embedded scripts in their README. When other users view the package in SiYuan's marketplace UI, the payload executes in the Electron context with full application privileges, enabling arbitrary code execution on the user's machine. This issue has been fixed in version 3.6.4.

• 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.