CVE-2013-4238 Security feature bypass in n/a

Medium 4.3 Published 18 Aug 2013 Updated 6 Aug 2024

Man-in-the-middle attackers can spoof SSL servers by exploiting a null byte handling flaw in Python's hostname matching, bypassing certificate validation.

Exploited in the wild: Not known
Login needed: Not needed
Attackable: Over the internet
Victim action needed: Not needed
Fix: Available

What is CVE-2013-4238?

CVE-2013-4238 is a medium-severity vulnerability in Canonical Ubuntu Linux, published on 18 Aug 2013. An attacker can exploit it over the internet without logging in, with no action from the victim.

Official 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.

Weakness: CWE-20

Which versions are affected by CVE-2013-4238?

It affects 3 products.

Linux distribution packages (28)

`python` Red Hat:enterprise_linux:6::client	All versions	`0:2.6.6-51.el6`
`python-debuginfo` Red Hat:enterprise_linux:6::client	All versions	`0:2.6.6-51.el6`
`python-devel` Red Hat:enterprise_linux:6::client	All versions	`0:2.6.6-51.el6`
`python-libs` Red Hat:enterprise_linux:6::client	All versions	`0:2.6.6-51.el6`
`python-test` Red Hat:enterprise_linux:6::client	All versions	`0:2.6.6-51.el6`
`python-tools` Red Hat:enterprise_linux:6::client	All versions	`0:2.6.6-51.el6`
`tkinter` Red Hat:enterprise_linux:6::client	All versions	`0:2.6.6-51.el6`
`python` Red Hat:enterprise_linux:6::computenode	All versions	`0:2.6.6-51.el6`
`python-debuginfo` Red Hat:enterprise_linux:6::computenode	All versions	`0:2.6.6-51.el6`
`python-devel` Red Hat:enterprise_linux:6::computenode	All versions	`0:2.6.6-51.el6`
`python-libs` Red Hat:enterprise_linux:6::computenode	All versions	`0:2.6.6-51.el6`
`python-test` Red Hat:enterprise_linux:6::computenode	All versions	`0:2.6.6-51.el6`
`python-tools` Red Hat:enterprise_linux:6::computenode	All versions	`0:2.6.6-51.el6`
`tkinter` Red Hat:enterprise_linux:6::computenode	All versions	`0:2.6.6-51.el6`
`python` Red Hat:enterprise_linux:6::server	All versions	`0:2.6.6-51.el6`
`python-debuginfo` Red Hat:enterprise_linux:6::server	All versions	`0:2.6.6-51.el6`
`python-devel` Red Hat:enterprise_linux:6::server	All versions	`0:2.6.6-51.el6`
`python-libs` Red Hat:enterprise_linux:6::server	All versions	`0:2.6.6-51.el6`
`python-test` Red Hat:enterprise_linux:6::server	All versions	`0:2.6.6-51.el6`
`python-tools` Red Hat:enterprise_linux:6::server	All versions	`0:2.6.6-51.el6`
`tkinter` Red Hat:enterprise_linux:6::server	All versions	`0:2.6.6-51.el6`
`python` Red Hat:enterprise_linux:6::workstation	All versions	`0:2.6.6-51.el6`
`python-debuginfo` Red Hat:enterprise_linux:6::workstation	All versions	`0:2.6.6-51.el6`
`python-devel` Red Hat:enterprise_linux:6::workstation	All versions	`0:2.6.6-51.el6`
`python-libs` Red Hat:enterprise_linux:6::workstation	All versions	`0:2.6.6-51.el6`
`python-test` Red Hat:enterprise_linux:6::workstation	All versions	`0:2.6.6-51.el6`
`python-tools` Red Hat:enterprise_linux:6::workstation	All versions	`0:2.6.6-51.el6`
`tkinter` Red Hat:enterprise_linux:6::workstation	All versions	`0:2.6.6-51.el6`

Products include Canonical Ubuntu Linux, Opensuse Opensuse, Python Python.

How do I fix CVE-2013-4238?

Upgrade to a fixed version.

Is CVE-2013-4238 being exploited?

There is no known exploitation of CVE-2013-4238 in the wild and no public exploit code.

All Canonical Ubuntu Linux vulnerabilities

Sources

Also known as CVE-2013-4328, DEBIAN-CVE-2013-4238, GHSA-vp8q-678w-8xq9, MGASA-2013-0250, PSF-2013-2, RHSA-2013:1582.