How severe is CVE-2013-2099?

CVE-2013-2099 has a CVSS 2.0 base score of 4.3, rated medium severity.

Is CVE-2013-2099 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 5% (91st percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2013-2099?

CVE-2013-2099 primarily affects Python. In total, 12 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.

How do I fix CVE-2013-2099?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.

When was CVE-2013-2099 published?

CVE-2013-2099 was published on 2013-10-09 and last updated on 2026-06-16.

CVE-2013-2099

CVE-2013-2099 is a medium-severity vulnerability in Python with a CVSS 2.0 base score of 4.3. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-399.

Key facts

Severity: Medium (CVSS 2.0 base score 4.3)
EPSS exploit prediction: 5% (91st percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-399
Affected product: Python
Published: 2013-10-09
Last modified: 2026-06-16

Description

Algorithmic complexity vulnerability in the ssl.match_hostname function in Python 3.2.x, 3.3.x, and earlier, and unspecified versions of python-backports-ssl_match_hostname as used for older Python versions, allows remote attackers to cause a denial of service (CPU consumption) via multiple wildcard characters in the common name in a certificate.

Frequently asked questions

What is CVE-2013-2099?: Algorithmic complexity vulnerability in the ssl.match_hostname function in Python 3.2.x, 3.3.x, and earlier, and unspecified versions of python-backports-ssl_match_hostname as used for older Python versions, allows remote attackers to cause a denial of service (CPU consumption) via multiple wildcard characters in the common name in a certificate.
How severe is CVE-2013-2099?: CVE-2013-2099 has a CVSS 2.0 base score of 4.3, rated medium severity.
Is CVE-2013-2099 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 5% (91st percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2013-2099?: CVE-2013-2099 primarily affects Python. In total, 12 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.
How do I fix CVE-2013-2099?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.
When was CVE-2013-2099 published?: CVE-2013-2099 was published on 2013-10-09 and last updated on 2026-06-16.

References

Affected products (12)

cpe:2.3:a:python:python:3.2.0:*:*:*:*:*:*:*
cpe:2.3:a:python:python:3.2.1:*:*:*:*:*:*:*
cpe:2.3:a:python:python:3.2.2:*:*:*:*:*:*:*
cpe:2.3:a:python:python:3.2.3:*:*:*:*:*:*:*
cpe:2.3:a:python:python:3.2.4:*:*:*:*:*:*:*
cpe:2.3:a:python:python:3.2.5:*:*:*:*:*:*:*
cpe:2.3:a:python:python:3.3.0:*:*:*:*:*:*:*
cpe:2.3:a:python:python:3.3.1:*:*:*:*:*:*:*
cpe:2.3:a:python:python:3.3.2:*:*:*:*:*:*:*
cpe:2.3:o:canonical:ubuntu_linux:12.04:-:lts:*:*:*:*:*
cpe:2.3:o:canonical:ubuntu_linux:12.10:*:*:*:*:*:*:*
cpe:2.3:o:canonical:ubuntu_linux:13.04:*:*:*:*:*:*:*

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Other CWE-399 (Resource Management Errors) vulnerabilities

CVE-2015-8104 — Critical (CVSS 10.0): The KVM subsystem in the Linux kernel through 4.2.6, and Xen 4.3.x through 4.6.x, allows guest OS users to cause a…
CVE-2015-0339 — Critical (CVSS 10.0): Adobe Flash Player before 13.0.0.277 and 14.x through 17.x before 17.0.0.134 on Windows and OS X and before…
CVE-2015-0335 — Critical (CVSS 10.0): Adobe Flash Player before 13.0.0.277 and 14.x through 17.x before 17.0.0.134 on Windows and OS X and before…
CVE-2015-0333 — Critical (CVSS 10.0): Adobe Flash Player before 13.0.0.277 and 14.x through 17.x before 17.0.0.134 on Windows and OS X and before…
CVE-2014-4121 — Critical (CVSS 10.0): Microsoft .NET Framework 2.0 SP2, 3.5, 3.5.1, 4, 4.5, 4.5.1, and 4.5.2 does not properly parse internationalized…
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