JWT Algorithm Confusion
Critical · Authentication · CWE-347
Description
Server accepts unexpected alg (none/HS/RS confusion).
Root cause
Custom JWT validation bugs.
Impact
Forged tokens, privilege escalation.
Detection
alg header tampering tests.
Mitigation
Allow-list algorithms; use vetted JWT libs.
Secure coding
Reject none; separate keys for HS vs RS.
Safe lab example
lab-jwt-alg
Practise related skills in Labs or deepen on Academy library.