Mozilla Firefox before 2.0.0.17 and 3.x before 3.0.2, Thunderbird before 2.0.0.17, and SeaMonkey before 1.1.12 allow remote attackers to bypass cross-site scripting (XSS) protection mechanisms and conduct XSS attacks via byte order mark (BOM) characters that are removed from JavaScript code before execution, aka "Stripped BOM characters bug."

Heap-based buffer overflow in pcrecompile.c in the Perl-Compatible Regular Expression (PCRE) library 7.7 allows context-dependent attackers to cause a denial of service (crash) or possibly execute arbitrary code via a regular expression that begins with an option and contains multiple branches.