VulnerabilityAnalyzed

CVE-2026-32245

A malicious OIDC client operator can exchange another client's authorization code using their own client credentials, obtaining tokens for users who never authorized their application.

MEDIUM 6.5EPSS 0.25%

Does this matter?

Lower severity and a low EPSS score (0.25%). Track it; it rarely justifies an emergency change on its own.

Description

Tinyauth is an authentication and authorization server. Prior to 5.0.3, the OIDC token endpoint does not verify that the client exchanging an authorization code is the same client the code was issued to. A malicious OIDC client operator can exchange another client's authorization code using their own client credentials, obtaining tokens for users who never authorized their application. This violates RFC 6749 Section 4.1.3. This vulnerability is fixed in 5.0.3.

CVSS 3.1: 6.5 MEDIUMCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:H/A:N
EPSS: 0.25% probability · 16th percentile
CISA KEV: Not listed
Weakness: CWE-863
Affected: tinyauth/tinyauth
Source: security-advisories@github.com

References

https://github.com/steveiliop56/tinyauth/commit/b2a1bfb1f532e87f205fa3afa3fc9f148c53ab89Patch
https://github.com/steveiliop56/tinyauth/releases/tag/v5.0.3Release Notes
https://github.com/steveiliop56/tinyauth/security/advisories/GHSA-xg2q-62g2-cvcmExploit, Third Party Advisory

Source: NVD record, EPSS from FIRST.org, KEV from CISA. Refreshed daily.