Security Information / 2013 / Security Information -- DSA-2763-1 pyopenssl

Debian Security Advisory

DSA-2763-1 pyopenssl -- hostname check bypassing

Date Reported:

24 Sep 2013

Affected Packages:

pyopenssl

Vulnerable:

Yes

Security database references:

In the Debian bugtracking system: Bug 722055.
In Mitre's CVE dictionary: CVE-2013-4314.

More information:

It was discovered that PyOpenSSL, a Python wrapper around the OpenSSL library, does not properly handle certificates with NULL characters in the Subject Alternative Name field.

A remote attacker in the position to obtain a certificate for 'www.foo.org\0.example.com' from a CA that a SSL client trusts, could use this to spoof www.foo.org and conduct man-in-the-middle attacks between the PyOpenSSL-using client and the SSL server.

For the oldstable distribution (squeeze), this problem has been fixed in version 0.10-1+squeeze1.

For the stable distribution (wheezy), this problem has been fixed in version 0.13-2+deb7u1.

For the unstable distribution (sid), this problem has been fixed in version 0.13-2.1.

We recommend that you upgrade your pyopenssl packages.