High

Pycrypto generates weak key parameters

Disclosed: 03.02.2018
Updated: 11.10.2026 11:20

lib/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.

Affected software

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Platform	Package	Vulnerable versions	Fixed in
Python (PyPI)	pycrypto	<= 2.6.1	no fix

References

CVSS score 7.5/10

CVSS vector: CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N
Weakness (CWE): CWE-326
Platform: Python (PyPI)
Package: pycrypto
Disclosed: 03.02.2018
Updated: 11.10.2026 11:20

Sources and licenses

OSV / GitHub Advisory Database - PYSEC-2018-97 - PyPA Advisory Database; CC BY 4.0

OSV / GitHub Advisory Database - GHSA-6528-wvf6-f6qg - CC BY 4.0

Vulnerability history: pycrypto

All published vulnerabilities of this package (Python (PyPI)), newest first. Shows whether this is a one-off slip or a package that needs watching.

Total entries: 4
First → latest: 06.2012 02.2018
Without a fix: 2
Exploited in attacks: 0

Severity breakdown

Critical 1
High 2
Medium 1

Disclosures per year

2017: 1
2018: 1
2019: 0
2020: 0
2021: 0
2022: 0
2023: 0
2024: 0
2025: 0
2026: 0

earlier: 2

03.02.2018

Pycrypto generates weak key parameters this entry

High · 7.5 CVE-2018-6594 <= 2.6.1 no fix
15.02.2017

Buffer Overflow in pycrypto

Critical · 9.8 CVE-2013-7459 <= 2.6.1 no fix
26.10.2013

The Crypto.Random.atfork function in PyCrypto before 2.6.1 does not properly reseed the pseudo-random number generator (PRNG) before allowing a child process to access it, which makes it easier for co

High · 7.5 CVE-2013-1445 < 2.6.1 2.6.1
17.06.2012

PyCrypto before 2.6 does not produce appropriate prime numbers when using an ElGamal scheme to generate a key, which reduces the signature space or public key space and makes it easier for attackers t

Medium · 5.3 CVE-2012-2417 < 2.6 2.6

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