DescriptionA 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.
SourceCVE (at NVD; CERT, LWN, oss-sec, fulldisc, Red Hat, Ubuntu, Gentoo, SUSE bugzilla/CVE, GitHub advisories/code/issues, web search, more)
Debian Bugs904072

Vulnerable and fixed packages

The table below lists information on source packages.

Source PackageReleaseVersionStatus
python-cryptography (PTS)bullseye3.3.2-1fixed
bookworm (security)38.0.4-3~deb12u1fixed
sid, trixie42.0.5-2fixed

The information below is based on the following data on fixed versions.

PackageTypeReleaseFixed VersionUrgencyOriginDebian Bugs
python-cryptographysourcejessie(not affected)
python-cryptographysourcestretch(not affected)


[stretch] - python-cryptography <not-affected> (Vulnerable code introduced later)
[jessie] - python-cryptography <not-affected> (Vulnerable code introduced later)

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