Joshua Rogers discovered a format string vulnerability in the yyerror function in lib/cgraph/scan.l in Graphviz, a rich set of graph drawing tools. An attacker could use this flaw to cause graphviz to crash or possibly execute arbitrary code.
For the stable distribution (wheezy), this problem has been fixed in version 2.26.3-14+deb7u2.
For the upcoming stable distribution (jessie), this problem will be fixed soon in version 2.38.0-7.
For the unstable distribution (sid), this problem has been fixed in version 2.38.0-7.
We recommend that you upgrade your graphviz packages.