2018-05-31 20:00:00
hackerone
PUBLISHED
Since "algorithm" isnt enforced in jwt.decode()in jwt-simple 0.3.0 and earlier, a malicious user could choose what algorithm is sent sent to the server. If the server is expecting RSA but is sent HMAC-SHA with RSAs public key, the server will think the public key is actually an HMAC private key. This could be used to forge any data an attacker wants.