Recommended action window: Monitor and triage in normal cycle
NVD description
Authlib is a Python library which builds OAuth and OpenID Connect servers. Prior to 1.9.1, Authlib's OctKey.import_key() and HMAC signing and verification path accept zero-length key material. If an application's secret lookup can return an empty string or empty bytes, a remote attacker can compute the deterministic HS256, HS384, or HS512 signature for arbitrary token claims and have Authlib treat the token as authentic. This issue is fixed in version 1.9.1.
Priority
LOW
Exploitation
NONE
PoC
NONE
Patch
NONE
Momentum
NONE
🚨HIGH - Authlib JWT Signature Forgery (CVE-2026-114615 + CVE-2026-114616) Authlib allows HMAC key confusion:Empty secret accepted → deterministic HS256/384/512 forgery, Prefixed PEM/public keys treated as HMAC secrets (bypass of previous fix)Attackers can forge JWTs with arbitrary claims and bypass auth. 👉Affected: authlib < 1.9.1 | Upgrade to 1.9.1