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CVE-2026-33544

Tinyauth race condition

7.7 HIGHPublic exploitEPSS 0.33%
  1. Published2 Apr 2026

Description

Tinyauth is an authentication and authorization server. Prior to version 5.0.5, all three OAuth service implementations (GenericOAuthService, GithubOAuthService, GoogleOAuthService) store PKCE verifiers and access tokens as mutable struct fields on singleton instances shared across all concurrent requests. When two users initiate OAuth login for the same provider concurrently, a race condition between VerifyCode() and Userinfo() causes one user to receive a session with the other user's identity. This issue has been patched in version 5.0.5.

CVSS 3.1 breakdown

Attack vectorNetwork
Attack complexityHigh
Privileges requiredLow
User interactionRequired
ScopeChanged
ConfidentialityHigh
IntegrityHigh
AvailabilityNone
CVSS:3.1/AV:N/AC:H/PR:L/UI:R/S:C/C:H/I:H/A:N

Affected products

Tinyauth< 5.0.5

Remediation

Fixed in
Tinyauth≥ 5.0.5

References

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Frequently asked

Is CVE-2026-33544 being actively exploited?

CVE-2026-33544 is not in the CISA KEV catalog. A public exploit reference exists, so treat it as exploitable. Its EPSS exploit probability is 0.33%.

How severe is CVE-2026-33544?

CVE-2026-33544 has a CVSS 3.1 base score of 7.7, rated high. EPSS estimates a 0.33% probability of exploitation.

Which products are affected by CVE-2026-33544?

Affected products include Tinyauth.

How do I fix CVE-2026-33544?

Upgrade affected software to a fixed version, for example Tinyauth 5.0.5 or later, then confirm no affected versions remain in your inventory.

How Secuno handles this

Secuno correlates vulnerabilities like CVE-2026-33544 against the real software inventory on every managed device, every day. Rather than a static severity, each match is scored in context: exploit availability, EPSS, the asset's exposure, and business criticality decide where it lands in the queue. If an affected version is present anywhere across your portfolio, it surfaces automatically with a prioritised remediation path.

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Data from the NVD, CISA KEV catalog and FIRST EPSS. CVSS 3.1 base score shown where available.