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CVE-2013-4238

15
FAUCET Score

CVE-2013-4238 describes a vulnerability in the ssl.match_hostname function within Python versions 2.6 through 3.4, where a null character in the Subject Alternative Name field of an X.509 certificate is mishandled. This flaw allows man-in-the-middle attackers to spoof SSL servers using specially crafted certificates from legitimate Certificate Authorities, affecting various Canonical, openSUSE, and Python distributions. The vulnerability has a CVSS score of 4.3 (Medium), indicating a network-based attack with medium complexity, requiring no authentication, and resulting in partial integrity impact. There is no evidence of active exploitation, publicly available exploit code in Metasploit, Nuclei, or ExploitDB, and it is not listed in CISA's KEV catalog, with minimal community discussion and media coverage.

Impacted Technologies

VendorProductVersion(s)CPE
10.04CPE matchmatch criteria
cpe:2.3:o:canonical:ubuntu_linux:10.04:-:lts:*:*:*:*:*
2.6.1CPE matchmatch criteria
cpe:2.3:a:python:python:2.6.1:*:*:*:*:*:*:*
2.6.2CPE matchmatch criteria
cpe:2.3:a:python:python:2.6.2:*:*:*:*:*:*:*
2.6.3CPE matchmatch criteria
cpe:2.3:a:python:python:2.6.3:*:*:*:*:*:*:*
2.6.4CPE matchmatch criteria
cpe:2.3:a:python:python:2.6.4:*:*:*:*:*:*:*

CVSS Data

CVSS version used by this source: 2.0

4.3MEDIUM

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

Confidentiality Impact
NONE
Integrity Impact
PARTIAL
Availability Impact
NONE
Access Vector
NETWORK
Access Complexity
MEDIUM
Authentication
NONE
Exploitability Score
8.6
Impact Score
2.9
CvssVersion
2.0

Exploit Intelligence

EPSS Score
5.35%
Probability of exploitation in next 30 days
EPSS Percentile
91.8%
Percentile rank of EPSS score among Peer Group
As of 2026-07-28
Model: v2026.06.15
This CVE's current EPSS score of 0.0535 is in the 90th percentile among its peer group of 19,958 CVEs.

Social Chatter

No social media mentions found for this CVE.

The average CVE in this peer group has 0.0 Twitter, 0.0 Reddit, 0.0 Bluesky, 0.0 Mastodon, and 0.2 GitHub mentions.

Media Mentions

The average CVE in this peer group has 0.0 InfoSec Media, 0.0 Vendor Blog, and 0.0 Security Researcher mentions.

Remediation

Patch Available

Vendor Patches (7)

asteriskpatch availablevia llm_extracted
Fixed in: 4.1.5/4.2.0
View patch
check_pointpatch availablevia llm_extracted
Fixed in: 4.1.5/4.2.0
View patch
redhatpatch availablevia redhat_api
Product: RHEV 3.X Hypervisor and Agents for RHEL-6Fixed in: rhev-hypervisor6-0:6.5-20131115.0.3.2.el6_5
View patch
redhatpatch availablevia redhat_api
Product: Red Hat Enterprise Linux 6Fixed in: python-0:2.6.6-51.el6
View patch
redhatpatch availablevia nvd_reference
View patch
susevendor investigatingvia nvd_reference
View patch
ubuntuvendor investigatingvia nvd_reference
View patch

Vendor Advisories (3)

redhatCVE-2013-4238Moderate

python: hostname check bypassing vulnerability in SSL module

Aug 12, 2013
asteriskllm-asterisk-d090c2206aedcbd7

Python Multiple Vulnerabilities

check_pointllm-check_point-f6cdf3e5f99bcbc9

Python Multiple Vulnerabilities

References

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