Vulnerability: Insecure Tag Length Validation in python-cryptography

CVE-2018-10903 · MEDIUM Severity

AV:N/AC:L/AU:N/C:P/I:N/A:N

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.

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