Use-after-free vulnerability in the nsNodeUtils::LastRelease function in the table-editing user interface in the editor component in Mozilla Firefox before 26.0, Firefox ESR 24.x before 24.2, Thunderbird before 24.2, and SeaMonkey before 2.23 allows remote attackers to execute arbitrary code by triggering improper garbage collection.
The product reuses or references memory after it has been freed. At some point afterward, the memory may be allocated again and saved in another pointer, while the original pointer references a location somewhere within the new allocation. Any operations using the original pointer are no longer valid because the memory "belongs" to the code that operates on the new pointer.