Mozilla Firefox and Thunderbird Closed Generator Handling Vulnerability Leading to Null Pointer Dereference

A vulnerability exists in the JavaScript engine of Mozilla Firefox and Thunderbird due to improper handling of closed generators. This issue allows for the resumption of these generators, resulting in a null pointer dereference. The vulnerability affects multiple versions of Firefox and Thunderbird, including Firefox through 140, Firefox ESR prior to 115.26, Firefox ESR prior to 128.13, Firefox ESR prior to 140.1, Thunderbird through 140, Thunderbird ESR prior to 115.26, Thunderbird ESR prior to 128.13, and Thunderbird ESR prior to 140.1.

Impact

Exploitation of this vulnerability leads to a null pointer dereference, causing a crash and potentially allowing for further exploitation.

Reproduction

The vulnerability can be reproduced by creating a closed generator in JavaScript and attempting to resume it. This can be done by using the 'next' method on the generator, which should not be possible if the generator is properly closed.

Remediation

Users can upgrade to Firefox 141, Firefox ESR 115.26, Firefox ESR 128.13, Firefox ESR 140.1, Thunderbird 141, or Thunderbird ESR 128.13.