Auth bypass in B3log Siyuan
CVE-2026-33203
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.
Published · last modified .
CVSS v3 metric
CVSS v3 base score 7.5 (High). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H.
EPSS exploit prediction
EPSS: 0.006 (45.3th percentile), scored .
Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 45th percentile — 45.3% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.
EPSS over last 30 days · oldest: 0.005 · newest: 0.006 · change: +0.001
Affected products
- B3log Siyuan
- Siyuan-Note Siyuan — versions < 3.6.2
Weakness classification (CWE)
References
- github.com/siyuan-note/siyuan/security/advisories/GHSA-3g9h-9hp4-654v (Exploit, Vendor Advisory)
Frequently asked questions
- What is CVE-2026-33203?
- CVE-2026-33203 is a high-severity vulnerability in B3log Siyuan, classified under CWE-248. CVSS score: 7.5/10. Published 2026-03-20.
- How severe is CVE-2026-33203?
- High severity. CVSS v3 base score is 7.5 out of 10.