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.
The product receives input or data, but it does not validate or incorrectly validates that the input has the properties that are required to process the data safely and correctly.
| Link | Tags |
|---|---|
| https://access.redhat.com/errata/RHSA-2018:3600 | vendor advisory |
| https://usn.ubuntu.com/3720-1/ | third party advisory vendor advisory |
| https://bugzilla.redhat.com/show_bug.cgi?id=CVE-2018-10903 | patch third party advisory issue tracking |
| https://github.com/pyca/cryptography/pull/4342/commits/688e0f673bfbf43fa898994326c6877f00ab19ef | third party advisory patch |