Published: 20 July 2018
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.
CVSS 3 base score: 7.5
Launchpad, Ubuntu, Debian
|Ubuntu 18.04 LTS (Bionic Beaver)||
|Ubuntu 16.04 ESM (Xenial Xerus)||
(code not present)
|Ubuntu 14.04 ESM (Trusty Tahr)||
Does not exist
following what debian says, our xenial version is not affected.