Authlib is vulnerable to Denial of Service via Oversized JOSE Segments

SummaryAuthlib’s JOSE implementation accepts unbounded JWS/JWT header and signature segments. A remote attacker can craft a token whose base64url‑encoded header or signature spans hundreds of megabytes. During verification, Authlib decodes and parses the full input before it is rejected, driving...

Denial Of Service (DoS)

Authlib is vulnerable to Denial-Of-Service via Oversized JWS/JWT. The vulnerability is due to Authlib accepting base64url-encoded header or signature inputs of unbounded size, allowing attackers to send tokens with huge encoded header/signature fields that exhaust CPU and memory during verificati...

CVE-2025-61920 Authlib is vulnerable to Denial of Service via Oversized JOSE Segments

Authlib is a Python library which builds OAuth and OpenID Connect servers. Prior to version 1.6.5, Authlib’s JOSE implementation accepts unbounded JWS/JWT header and signature segments. A remote attacker can craft a token whose base64url‑encoded header or signature spans hundreds of megabytes...