CVE-2018-6594

NameCVE-2018-6594
Descriptionlib/Crypto/PublicKey/ElGamal.py in PyCrypto through 2.6.1 generates weak ElGamal key parameters, which allows attackers to obtain sensitive information by reading ciphertext data (i.e., it does not have semantic security in face of a ciphertext-only attack). The Decisional Diffie-Hellman (DDH) assumption does not hold for PyCrypto's ElGamal implementation.
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 Bugs889998, 889999

Vulnerable and fixed packages

The table below lists information on source packages.

Source PackageReleaseVersionStatus
pycryptodome (PTS)buster, sid3.6.1-2fixed
python-crypto (PTS)jessie2.6.1-5+deb8u1vulnerable
stretch2.6.1-7vulnerable
buster, sid2.6.1-9fixed

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

PackageTypeReleaseFixed VersionUrgencyOriginDebian Bugs
pycryptodomesource(unstable)3.4.11-1medium889998
python-cryptosource(unstable)2.6.1-9medium889999

Notes

[stretch] - python-crypto <no-dsa> (Minor issue)
[jessie] - python-crypto <no-dsa> (Minor issue)
[wheezy] - python-crypto <no-dsa> (Minor issue)
PyCrypto: https://github.com/dlitz/pycrypto/issues/253
The issue is found as well in pycryptodome (fork from python-crypto)
PyCryptodome: https://github.com/Legrandin/pycryptodome/issues/90
PyCrytpodome: https://github.com/Legrandin/pycryptodome/commit/99c27a3b9e8a884bbde0e88c63234b669d4398d8 (3.4.10)
See further discussion as per https://github.com/Legrandin/pycryptodome/issues/90#issuecomment-362783537
Upstream feels that this is not a vulnerability in pycryptodome/python-crypto,
but in an application using it in an insecure manner.

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