PyJWT: HS256/384/512 verify accepts empty HMAC key via oct JWK (PyJWK/PyJWKClient) enabling token forgery
影響: pip:pyjwt <= 2.13.0 → 2.14.0
HMACAlgorithm.from_jwk accepts a symmetric (kty=oct) JWK whose k value is the empty string and returns a zero-length key without raising. When a token is then verified with that key object (a PyJWK, or a PyJWK resolved by PyJWKSet / PyJWKClient), the HMAC verifier computes HMAC(key=b"", signing_input) and accepts any token an attacker forged with the same empty key. The attacker needs no secret knowledge: they reproduce the digest locally with an empty key and set the token's kid to the empty-k…
| 情報源 | GitHub Advisory Database |
|---|---|
| 取得日時 | 2026/10/23 05:09 |
| データ | Markdown JSON |
2026/10/23 00:48、GitHub Advisory Databaseが「PyJWT: HS256/384/512 verify accepts empty HMAC key via oct JWK (PyJWK/PyJWKClient) enabling token forgery」を公開しました (種別: 脆弱性アドバイザリ)。重大度は「重要」(high) です。関連する技術: Python。