PYSEC-2026-4183: PyJWT accepts inconsistent OKP x/d JWKs, causing public/private key identity confusion

PyJWT is a Python implementation of JSON Web Token standards. From 2.1.0 until 2.15.0, PyJWT OKPAlgorithm.fromjwk in jwt/algorithms.py is affected because private-JWK import path does not compare the public key derived from d with x. This occurs when an OKP private JWK supplies non-corresponding x and d components. As a result, identity derived from x can differ from operations performed with d. Consequently, if an integration also accepts private key parameters from a proof header without rejecting them, an attacker may use a stolen sender-constrained token without the legitimate private key. This issue is fixed in version 2.15.0.