PyJWT accepts inconsistent OKP JWKs, allowing key identity confusion

PyJWT fails to validate that the public key parameter 'x' matches the key derived from private key parameter 'd' in OKP JWKs, allowing attackers to use stolen sender-constrained tokens without the legitimate holder's private key in DPoP integrations.

Disclosed 5 October 2026 · Record updated 6 October 2026

Impact

In DPoP integrations, a stolen sender-constrained access token can be used without possession of the legitimate holder's private key due to inconsistent OKP JWK validation.

Our coverage

A locksmith hands a stranger a key cut from someone else's lock, unknowingly pairing mismatched tumblers that now open doors to restricted rooms.

Vulnerabilities

PyJWT accepts mismatched Ed25519 key pairs in JWK imports

A flaw disclosed on 5 October 2026 lets a crafted JSON Web Key pair one user's public key with an attacker's private key, breaking DPoP token binding.

6 Oct 2026

Sources

github.comhttps://github.com/advisories/GHSA-x33g-cr3x-6449