Vulnerability in Siyuan-Note Siyuan
CVE-2026-73056
SiYuan kernel versions before 3.7.4 contain an improper restriction of excessive authentication attempts vulnerability in the CheckAuth() middleware. The middleware accepts the API token (Conf.Api.Token) via an Authorization header (Token/Bearer) or a ?token= query parameter, and neither path is protected by the application's CAPTCHA/lockout mechanism (NeedCaptcha/WrongAuthCount). As a result, an unauthenticated remote attacker can perform unlimited automated guesses of the API token, particularly when a short or weak custom token has been configured, and upon success gains full RoleAdministrator access enabling arbitrary file operations and SQL queries.
Published · last modified .
CVSS v3 metric
CVSS v3 base score 9.8 (Critical). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H.
EPSS exploit prediction
EPSS: 0.008 (54.6th percentile), scored .
Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 55th percentile — 54.6% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.
EPSS over last 30 days · oldest: 0.004 · newest: 0.008 · change: +0.003
Affected products
- Siyuan-Note Siyuan — versions 0, 3.7.4
Weakness classification (CWE)
References
- github.com/siyuan-note/siyuan/security/advisories/GHSA-m6w6-p7pc-fpg2 (vendor-advisory)
- www.vulncheck.com/advisories/siyuan-kernel-before-unthrottled-brute-force-via-a… (third-party-advisory)
Frequently asked questions
- What is CVE-2026-73056?
- CVE-2026-73056 is a critical-severity vulnerability in Siyuan-Note Siyuan, classified under Improper Restriction of Excessive Authentication Attempts. CVSS score: 9.8/10. Published 2026-08-16.
- How severe is CVE-2026-73056?
- Critical severity. CVSS v3 base score is 9.8 out of 10.