Multiple vulnerabilities has been found and corrected in t1lib:

A heap-based buffer overflow flaw was found in the way AFM font file
parser, used for rendering of DVI files, in GNOME evince document
viewer and other products, processed line tokens from the given input
stream. A remote attacker could provide a DVI file, with embedded
specially-crafted font file, and trick the local user to open it with
an application using the AFM font parser, leading to that particular
application crash or, potentially, arbitrary code execution with the
privileges of the user running the application. Different vulnerability
than CVE-2010-2642 (CVE-2011-0433).

t1lib 5.1.2 and earlier reads from invalid memory locations, which
allows remote attackers to cause a denial of service (application
crash) via a crafted Type 1 font in a PDF document, a different
vulnerability than CVE-2011-0764 (CVE-2011-1552).

Use-after-free vulnerability in t1lib 5.1.2 and earlier allows
remote attackers to cause a denial of service (application crash)
via a PDF document containing a crafted Type 1 font that triggers an
invalid memory write, a different vulnerability than CVE-2011-0764
(CVE-2011-1553).

Off-by-one error in t1lib 5.1.2 and earlier allows remote attackers
to cause a denial of service (application crash) via a PDF document
containing a crafted Type 1 font that triggers an invalid memory
read, integer overflow, and invalid pointer dereference, a different
vulnerability than CVE-2011-0764 (CVE-2011-1554).

The updated packages have been patched to correct these issues.