7.5 - USN-251-1

A security issue affects the following Ubuntu releases:

Ubuntu 4.10 (Warty Warthog) Ubuntu 5.04 (Hoary Hedgehog) Ubuntu 5.10 (Breezy Badger)

The following packages are affected:

libtasn1-2 libgnutls10 libgnutls11

The problem can be corrected by upgrading the affected package to the following versions:

Ubuntu 4.10:
libtasn1-2: 0.2.7-2ubuntu0.1
libgnutls10: 1.0.4-3ubuntu1.2

Ubuntu 5.04:
libtasn1-2: 0.2.10-4ubuntu0.0.5.04.1
libgnutls11: 1.0.16-13ubuntu0.2

Ubuntu 5.10:
libtasn1-2: 0.2.10-4ubuntu0.1
libgnutls11: 1.0.16-13.1ubuntu1.1

It is highly recommended to restart your computer after a standard system upgrade to effect the necessary changes. If you cannot afford to do that then you need to restart all server processes which use TLS or SSL.

Details follow:

Evgeny Legerov discovered a buffer overflow in the DER format decoding function of the libtasn library. This library is mainly used by the GNU TLS library; by sending a specially crafted X.509 certificate to a server which uses TLS encryption/authentication, a remote attacker could exploit this to crash that server process and possibly even execute arbitrary code with the privileges of that server.

In order to fix the vulnerability in libtasn, several internal function signatures had to be changed; some of these functions are used by the GNU TLS library, so that library needs to be updated as well.