CVE-2026-33203: b3log siyuan Uncaught Exception

Vulnerability summary

CVE-2026-33203 is a high (CVSS 7.5) Uncaught Exception vulnerability in b3log siyuan. EPSS estimates a 0.60% chance of exploitation in the next 30 days, higher than 47.6% of scored vulnerabilities. 1 public exploit is recorded.

Timeline

1. 20-03-2026
   PublishedVulnerability first disclosed.
2. 23-03-2026
   Last modifiedVulnerability information updated.

Description

SiYuan is a personal knowledge management system. Prior to version 3.6.2, the SiYuan kernel WebSocket server accepts unauthenticated connections when a specific "auth keepalive" query parameter is present. After connection, incoming messages are parsed using unchecked type assertions on attacker-controlled JSON. A remote attacker can send malformed messages that trigger a runtime panic, potentially crashing the kernel process and causing denial of service. Version 3.6.2 fixes the issue.

• CWE-248Uncaught ExceptionAn exception is thrown from a function, but it is not caught.
• CWE-306Missing Authentication for Critical FunctionThe product does not perform any authentication for functionality that requires a provable user identity or consumes a significant amount of resources.