Ubuntu Security Notice USN-252-1 – Tavis Ormandy discovered a potential weakness in the signature verification of gnupg. gpgv and gpg –verify returned a successful exit code even if the checked file did not have any signature at all. The recommended way of checking the result is to evaluate the status messages, but some third party applications might just check the exit code for determining whether or not a signature is valid. These applications could be tricked into erroneously reporting a valid signature.
You can download this advisory from the following link: https://packetstormsecurity.com/files/download/43991/USN-252-1.txt
Source: https://packetstormsecurity.com/files/43991/Ubuntu-Security-Notice-252-1.html