What’s Vulnerable › Vulnerabilities

CVE-2026-73056: SiYuan kernel before 3.7.4 Unthrottled Brute-Force via API Token

• Severity: critical (CVSS 9.8 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.8% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2026-08-16 · updated 2026-08-26
• Weakness: CWE-307

Description

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.

Affected products

• siyuan-note siyuan: before 3.7.4 — fixed in 3.7.4

How to fix

Upgrade to a fixed version: siyuan-note siyuan 3.7.4. Check the vendor advisory for mitigations.

References

• https://github.com/siyuan-note/siyuan/security/advisories/GHSA-m6w6-p7pc-fpg2
• https://www.vulncheck.com/advisories/siyuan-kernel-before-unthrottled-brute-force-via-api-token
• https://github.com/siyuan-note/siyuan/security/advisories/GHSA-m6w6-p7pc-fpg2

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