Use After Free
A use-after-free vulnerability can occur when the thread for a Web Worker is freed from memory prematurely instead of from memory in the main thread while cancelling fetch operations. This vulnerability affects Firefox < 58.
CWE-416 - Use After Free
Use-after-free (UaF) vulnerability occurs when the application is using a pointer to memory that has been freed. Any attempt to read/write to a buffer after it is de-allocated allows memory corruption, sensitive information exposure, and can potentially lead to arbitrary code execution.