CVE-2026-73056Public exploitNetwork attack vectorHinoki check available

Administrator access via unthrottled API token guesses

Published Aug 16, 2026 · Updated Aug 16, 2026

Authentication brute force in CheckAuth() in SiYuan kernel before 3.7.4 allows remote attackers to gain administrator access via API token guessing. The middleware accepts Conf.Api.Token from Authorization Token or Bearer headers or from a token query parameter and compares it without invoking NeedCaptcha() or incrementing WrongAuthCount, so failed guesses are never throttled. Exposure requires a network-reachable kernel and becomes practical when a short or weak custom API token has been set; a successful guess immediately grants RoleAdministrator, enabling file operations and SQL queries.

CVSS severity9.8
Critical
EPSS probability0.45%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkAvailable
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Summary

What happened

Authentication brute force in CheckAuth() in SiYuan kernel before 3.7.4 allows remote attackers to gain administrator access via API token guessing. The middleware accepts Conf.Api.Token from Authorization Token or Bearer headers or from a token query parameter and compares it without invoking NeedCaptcha() or incrementing WrongAuthCount, so failed guesses are never throttled. Exposure requires a network-reachable kernel and becomes practical when a short or weak custom API token has been set; a successful guess immediately grants RoleAdministrator, enabling file operations and SQL queries.

The record

CVE
CVE-2026-73056
Published
Aug 16, 2026
Updated
Aug 16, 2026
Vendor
SiYuan Note
Product
SiYuan
Classifications
CWE-598, CWE-307, CWE-208, T1110.001
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Aug 16, 2026CVE publishedPublication date reported by the CVE source.
  2. Aug 16, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=0 <3.7.4

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

SiYuan Note · SiYuanversion=0 <3.7.4

Published CVSS scores

9.8GitHubCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

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No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-598Use of HTTP Request With Sensitive Query String
CWE-307Improper Restriction of Excessive Authentication Attempts
CWE-208Observable Timing Discrepancy
T1110.001Brute Force: Password Guessing

Public exploit references

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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