CVE-2018-10903

NameCVE-2018-10903
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, bugtraq, EDB, Metasploit, Red Hat, Ubuntu, Gentoo, SUSE bugzilla/CVE, Mageia, GitHub code/issues, web search, more)
NVD severitymedium (attack range: remote)
Debian Bugs904072

Vulnerable and fixed packages

The table below lists information on source packages.

Source PackageReleaseVersionStatus
python-cryptography (PTS)jessie0.6.1-1+deb8u1fixed
stretch1.7.1-3fixed
buster, sid2.3-1fixed

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

PackageTypeReleaseFixed VersionUrgencyOriginDebian Bugs
python-cryptographysource(unstable)2.3-1medium904072
python-cryptographysourcejessie(not affected)
python-cryptographysourcestretch(not affected)

Notes

[stretch] - python-cryptography <not-affected> (Vulnerable code introduced later)
[jessie] - python-cryptography <not-affected> (Vulnerable code introduced later)
https://github.com//pyca/cryptography/pull/4342
https://github.com/pyca/cryptography/pull/4342/commits/688e0f673bfbf43fa898994326c6877f00ab19ef

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