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Vulnerability record · CVE-2013-4238 · published 18 August 2013

CVE-2013-4238: Canonical ubuntu linux improper input validation vulnerability

Canonical · Ubuntu Linux

The ssl.match_hostname function in the SSL module in Python 2.6 through 3.4 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, a related issue to CVE-2009-2408.

4.3 CVSS 2.0 Medium EPSS 5.3% · top 7.7% CWE-20 · Improper input validation
4.3CVSS 2.0 base score
5.3%EPSS exploitation probability, 30 days
NoNot in CISA KEV
3Affected product versions listed by NVD
30References
16 Jun 2026Last modified by NVD

Description

The ssl.match_hostname function in the SSL module in Python 2.6 through 3.4 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, a related issue to CVE-2009-2408.

AV:N/AC:M/Au:N/C:N/I:P/A:N

Affected products

3 vulnerable configurations from NVD's CPE data, grouped by vendor and product.

References

LinkTags
http://bugs.python.org/issue18709 Patch
http://lists.opensuse.org/opensuse-security-announce/2020-01/msg00040.html
http://lists.opensuse.org/opensuse-updates/2013-09/msg00026.html Vendor Advisory
http://lists.opensuse.org/opensuse-updates/2013-09/msg00027.html Vendor Advisory
http://lists.opensuse.org/opensuse-updates/2013-09/msg00028.html Vendor Advisory
http://lists.opensuse.org/opensuse-updates/2013-09/msg00029.html Vendor Advisory
http://lists.opensuse.org/opensuse-updates/2013-09/msg00042.html Vendor Advisory
http://lists.opensuse.org/opensuse-updates/2013-09/msg00043.html Vendor Advisory
http://rhn.redhat.com/errata/RHSA-2013-1582.html
http://seclists.org/fulldisclosure/2014/Dec/23
http://www.debian.org/security/2014/dsa-2880
http://www.securityfocus.com/archive/1/534161/100/0/threaded
http://www.ubuntu.com/usn/USN-1982-1 Vendor Advisory
http://www.vmware.com/security/advisories/VMSA-2014-0012.html
https://bugzilla.redhat.com/show_bug.cgi?id=996381 Patch
http://bugs.python.org/issue18709 Patch
http://lists.opensuse.org/opensuse-security-announce/2020-01/msg00040.html
http://lists.opensuse.org/opensuse-updates/2013-09/msg00026.html Vendor Advisory
http://lists.opensuse.org/opensuse-updates/2013-09/msg00027.html Vendor Advisory
http://lists.opensuse.org/opensuse-updates/2013-09/msg00028.html Vendor Advisory
http://lists.opensuse.org/opensuse-updates/2013-09/msg00029.html Vendor Advisory
http://lists.opensuse.org/opensuse-updates/2013-09/msg00042.html Vendor Advisory
http://lists.opensuse.org/opensuse-updates/2013-09/msg00043.html Vendor Advisory
http://rhn.redhat.com/errata/RHSA-2013-1582.html
http://seclists.org/fulldisclosure/2014/Dec/23
http://www.debian.org/security/2014/dsa-2880
http://www.securityfocus.com/archive/1/534161/100/0/threaded
http://www.ubuntu.com/usn/USN-1982-1 Vendor Advisory
http://www.vmware.com/security/advisories/VMSA-2014-0012.html
https://bugzilla.redhat.com/show_bug.cgi?id=996381 Patch

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Source: NIST National Vulnerability Database (record CVE-2013-4238), CISA KEV, FIRST EPSS (scores of 2026-09-27). This page is refreshed as NVD updates the record.