The CERT_DecodeCertPackage function in Mozilla Network Security Services (NSS), as used in Mozilla Firefox before 20.0, Firefox ESR 17.x before 17.0.5, Thunderbird before 17.0.5, Thunderbird ESR 17.x before 17.0.5, SeaMonkey before 2.17, and other products, allows remote attackers to cause a denial of service (out-of-bounds read and memory corruption) via a crafted certificate.