A flaw was found in python-cryptography versions between >=1.9.0 and <2.3. The finalizewithtag API did not enforce a minimum tag length. If a user did not validate the input length prior to passing it to finalizewithtag an attacker could craft an invalid payload with a shortened tag (e.g. 1 byte) such that they would have a 1 in 256 chance of passing the MAC check. GCM tag forgeries can cause key leakage.
{ "nvd_published_at": null, "cwe_ids": [ "CWE-20" ], "severity": "HIGH", "github_reviewed": true, "github_reviewed_at": "2020-06-16T21:34:18Z" }