PyJWT: Public-key JWK accepted as HMAC secret enables forged HS256 tokens when mixed families are allowed

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CVE-2026-48526

PyJWT (Python) prior to 2.13.0 did not validate the use of JSON Web Keys in HMAC verification, allowing an attacker to use the issuer public key as the HMAC secret during token verification. This could enable forging tokens when mixing RS/EC/JWK and HS algorithms. The issue is fixed in PyJWT 2.13...