Mozilla Firefox and Thunderbird Branch Table Truncation Vulnerability on Arm64

A vulnerability exists in Mozilla Firefox and Thunderbird on arm64 architectures, where a WebAssembly 'br_table' instruction with numerous entries can cause the label to be too distant from the instruction. This distance can lead to truncation and incorrect calculation of the branch address. The issue is present in Firefox versions prior to 141, Firefox ESR versions prior to 115.26, 128.13, and 140.1, as well as in Thunderbird versions prior to 141, 128.13, and 140.1.

Impact

Exploitation of this vulnerability can result in incorrect branch address calculations, potentially leading to unintended control flow in the application.

Remediation

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