CVE 2012-0451
CRLF injection vulnerability in Mozilla Firefox 4.x through 10.0, Firefox ESR 10.x before 10.0.3, Thunderbird 5.0 through 10.0, Thunderbird ESR 10.x before 10.0.3, and SeaMonkey before 2.8 allows remote web servers to bypass intended Content Security Policy (CSP) restrictions and possibly conduct cross-site scripting (XSS) attacks via crafted HTTP headers.
See the 
CVE page on Mitre.org
for more details.
