High severity vulnerability that affects cryptography

2018-07-31T18:28:09
ID GHSA-FCF9-3QW3-GXMJ
Type github
Reporter GitHub Advisory Database
Modified 2019-07-03T21:02:02

Description

A flaw was found in python-cryptography versions between >=1.9.0 and <2.3. The finalize_with_tag API did not enforce a minimum tag length. If a user did not validate the input length prior to passing it to finalize_with_tag 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.