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CVE-2026-77561— Tinyauth: Unauthenticated login attempts can trigger global login lockdown denial of service

Quick assessment

Affected
tinyauthapp tinyauth
Exploitation
No confirmed in-the-wild exploitation; assess based on exposure
Recommended action
Check the vendor advisory and references for a fixed version. If immediate upgrade is impossible, restrict exposure and increase monitoring.

Tinyauth is an authentication and authorization server. Prior to 5.1.0, an unauthenticated remote attacker can send POST /api/user/login requests with 257 distinct nonexistent usernames to fill MaxLoginAttemptRecords and activate a global login lockdown. inter

CVSS 5.3 · Medium EPSS 0.48% · P41

Affected Version Matrix 1

VendorProduct Version RangeStatus
tinyauthapp tinyauth < 5.1.0 affected
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I. Basic Information for CVE-2026-77561

Vulnerability Information

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Vulnerability Title
Tinyauth: Unauthenticated login attempts can trigger global login lockdown denial of service
Source: CVE Program / CVE List V5
Vulnerability Description
Tinyauth is an authentication and authorization server. Prior to 5.1.0, an unauthenticated remote attacker can send POST /api/user/login requests with 257 distinct nonexistent usernames to fill MaxLoginAttemptRecords and activate a global login lockdown. internal/controller/user_controller.go loginHandler passes each attacker-controlled identifier to internal/service/auth_service.go RecordLoginAttempt, which invokes lockdownMode after the map reaches its cap. IsAccountLocked checks that global state before validating unrelated accounts, causing valid users to receive HTTP 429 until auth.loginTimeout expires, approximately 300 seconds by default. The attack can be repeated, but existing authenticated sessions are not invalidated. This issue is fixed in version 5.1.0.
Source: CVE Program / CVE List V5
CVSS Information
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L
Source: CVE Program / CVE List V5
Vulnerability Type
过多认证尝试的限制不恰当
Source: CVE Program / CVE List V5

Affected Products

Vendor Product Affected Versions CPE Subscribe
tinyauthapp tinyauth < 5.1.0 -

II. Public POCs for CVE-2026-77561

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III. Intelligence Information for CVE-2026-77561

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Patches & Fixes for CVE-2026-77561 (4)

Other References for CVE-2026-77561 (2)

Same Patch Batch · tinyauthapp · 2026-09-21 · 3 CVEs total

CVE-2026-77560 8.1 HIGH Tinyauth: forward-auth per-app ACL is matched case-sensitively against the (case-insensiti
CVE-2026-77582 6.9 MEDIUM Tinyauth: User enumeration attack by timing oracle

IV. Related Vulnerabilities

Same product: tinyauth
Same vendor: tinyauthapp
Same weakness: CWE-307

V. Comments for CVE-2026-77561

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