Threats tagged 'brew-fastmcp-cve-2026-119283'

The joserfc library's decrypt_json() function for JWE General JSON Serialization accepts an unbounded recipients array, performing a costly RSA private-key decryption for each recipient without limit. This allows an unauthenticated attacker to cause CPU exhaustion (Denial of Service) by sending a single JWE JSON with many recipients. The library caps sizes of other JWE elements but does not limit recipient count. The documented mitigation option verify_all_recipients=False does not reduce CPU usage, as all recipients are decrypted before this flag is checked. This vulnerability is tracked as CVE-2026-119283 with a CVSS 3.1 score of 7.5 (High). A fix is available in joserfc version 4.0.0.