Libpng 1.5.9, bundled in branch 13.0, is vulnerable to CVE-2011-3048 (see: http://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2011-3048 & http://www.libpng.org/pub/png/src/libpng-1.5.10-README.txt). The bundled version should be updated to version 1.5.10 across the board (firefox, thunderbird, etc.).
libpng was updated to 1.5.10 on April 25 for Mozilla Central. This means it is fixed in Firefox 15 and 16 now. See bug 745178 and https://hg.mozilla.org/mozilla-central/rev/f22a06ee6a6e Adding flags for affected versions (Firefox 14 and ESR).
Andrew, do you know of a testcase to check to see if we're vulnerable? We're not always susceptible to some of the png issues.
see bug 745178 comment from one of the libpng maintainers -- that CVE does not affect Firefox because it's in a feature we don't use.
repeating bug 745178 comment 0 for the convenience of linkability "The main reason for the release was to fix CVE-2011-3048, but we aren't vulnerable to that."
See also bug 737502
I didn't drill down to see if png_set_text2 (where the problem lies) is used by Mozilla either directly or indirectly. Figured I'd report it just in case. Good to know it isn't used - makes for an easy fix.
Not only is it not used, it is totally ignored via the png_set_keep_unknown_chunks() call in the PNG decoder. Therefore even mozilla builds that use the "system" libpng instead of the bundled libpng are safe.