Authlib accepts an empty HMAC key, allowing JWS/JWT signature forgery (HS256/HS384/HS512)

影響: pip:Authlib < 1.9.1 → 1.9.1

Reporter: Cavan Loughran, Celvex Group Inc. Summary Authlib's symmetric (oct) key handling accepts an empty key (empty bytes b'' / empty string '') as a valid HMAC signing and verification key. An empty HMAC key produces a deterministic digest that any party can reproduce, so an attacker who knows (or can cause) the application to verify a token with an empty key can forge arbitrary tokens that pass HS256/HS384/HS512 signature verification. This is the Authlib member of the cross-language empty…

GitHub Advisory Databaseで読む

2026/10/28 01:09、GitHub Advisory Databaseが「Authlib accepts an empty HMAC key, allowing JWS/JWT signature forgery (HS256/HS384/HS512)」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。CVE: CVE-2026-114616。