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Fencer Intel
high 7.5

CVE-2013-4314 json

PyOpenSSL Mishandles NUL Byte In Certificate Subject Alternative Name

published 13y ago modified 4mo ago also GHSA-6748-36qp-fx6r , PYSEC-2013-31 , EUVD-2013-0029

cvss
7.5
version 3.1, GitHub
cisa kev
Not listed
not in CISA's catalog
epss
1.2%
EPSS 1.2% chance of exploitation in 30 days, percentile 68%
public exploits
0
none known

Summary

The X509Extension in pyOpenSSL before 0.13.1 does not properly handle a '\0' character in a domain name in the Subject Alternative Name field of an X.509 certificate, which allows man-in-the-middle attackers to spoof arbitrary SSL servers via a crafted certificate issued by a legitimate Certification Authority.

Patch / fix

  • pypi pyopenssl 0.13.1
  • pyopenssl Debian 14, Debian 13, Debian 12 0.13-2.1

debian advisories DEBIAN-CVE-2013-4314

  • python-pyOpenSSL openSUSE Tumbleweed 26.4.0-1.1
  • python-pyOpenSSL openSUSE Tumbleweed 24.1.0-1.2

opensuse advisories openSUSE-SU-2026:11470-1openSUSE-SU-2024:14154-1

Is CVE-2013-4314 in your dependencies? Fencer shows which of your repositories are affected as soon as an advisory lands, and opens the fix as a pull request.

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Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2013-4314 updated cvss 4.3

pyOpenSSL: hostname check bypassing vulnerability

  • Red Hat Enterprise Linux 5 pyOpenSSL Red Hat Enterprise Linux 6 pyOpenSSL Red Hat Enterprise Linux 7 pyOpenSSL Red Hat OpenStack Platform 4 pyOpenSSL Red Hat Storage 2 pyOpenSSL
    not affected: vulnerable code not present

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

Exploit prediction

1.20% chance of exploitation in the next 30 days, higher than 68% of all scored CVEs (FIRST EPSS, 2026-11-09).

CVSS scores

assigned by version score vector
NVD 2.0 4.3 AV:N/AC:M/Au:N/C:N/I:P/A:N
GitHub 3.1 7.5 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N

Affected packages

ecosystem package affected fixed in
pypi pyopenssl
<0.13.1
0.13.1

Classification

Weakness
  • CWE-20 Improper Input Validation

References

Sources

Fencer Intel keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.