Multiple integer overflows in the (1) PL_Base64Decode and (2) PL_Base64Encode functions in nsprpub/lib/libc/src/base64.c in Mozilla Firefox before 3.0.12, Thunderbird before 2.0.0.24, and SeaMonkey before 1.1.19 allow remote attackers to cause a denial of service (memory corruption and application crash) or possibly execute arbitrary code via unspecified vectors that trigger buffer overflows.
Weaknesses in this category are related to improper calculation or conversion of numbers.