The CVE describes a flaw in Tinyauth's OIDC token endpoint where authorization codes are not bound to the client that received them, enabling a rogue OIDC client to redeem another client's code and obtain access tokens for the affected user. This results in unauthorized token issuance, effectively allowing an attacker to access protected resources without the user's consent. The weakness is a form of Missing Authorization as identified by CWE‑863.

The affected product is steveiliop56:Tinyauth, in all releases prior to version 5.0.3. Consequently, any deployment using Tinyauth 5.0.2 or earlier is vulnerable; version 5.0.3 and newer contain the fix.

The CVSS score is 6.5, indicating medium severity. EPSS shows less than 1% probability of exploitation, and the CVE is not listed in the CISA KEV catalog. Attackers can exploit the vulnerability by sending token exchange requests to the public endpoint with a valid authorization code issued to another client. The attack vector is network based and does not require additional privileges beyond the ability to communicate with the token endpoint.