Security issues were identified and fixed in mozilla firefox and thunderbird: An integer overflow in the libpng library can lead to a heap-buffer overflow when decompressing certain PNG images. This leads to a crash, which may be potentially exploitable . The mozilla firefox and thunderbird packages has been upgraded to the latest respective versions whish is not affecte dby this security flaw. Additionally the rootcerts packages has been upgraded to the latest version as of 2012/02/18 and the NSS library has been rebuilt accordingly to pickup the changes. Update: This is a symbolic advisory correction because there was a clash with MDVSA-2012:022 that addressed libpng.