The krb5 PAM module (pam_krb5.so) had a buffer overflow that might have caused remote code execution in situations involving supplemental prompting by a Kerberos library. It might have overflown a buffer provided by the underlying Kerberos library by a single '\0' byte if an attacker responded to a prompt with an answer of a carefully chosen length. The effect may have ranged from heap corruption to stack corruption depending on the structure of the underlying Kerberos library, with unknown effects but possibly including code execution. This code path had not been used for normal authentication, but only when the Kerberos library did supplemental prompting, such as with PKINIT or when using the non-standard no_prompt PAM configuration option.

For Debian 8 Jessie, this problem has been fixed in version 4.6-3+deb8u1.

We recommend that you upgrade your libpam-krb5 packages.

Further information about Debian LTS security advisories, how to apply these updates to your system and frequently asked questions can be found at: https://wiki.debian.org/LTS