CVE-2026-102273: PyJWT accepts public JWK containers as HMAC secrets

September 29, 2026

PyJWT 2.13.0 contains an incomplete defense against algorithm confusion when an application mixes symmetric and asymmetric algorithms in one verification path. A public RSA, EC, or OKP JWK can be accepted as an HMAC secret when it is wrapped in a JWKS object, nested in an array, or represented in another container form that does not expose a top-level kty member.

References

github.com/advisories/GHSA-w2cx-738m-mc7w
github.com/jpadilla/pyjwt/commit/801cd128528c62d9b23fcd161d1a2e1c17982f95
github.com/jpadilla/pyjwt/releases/tag/2.14.0
github.com/jpadilla/pyjwt/security/advisories/GHSA-w2cx-738m-mc7w
nvd.nist.gov/vuln/detail/CVE-2026-102273

Code Behaviors & Features

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