Mozilla security advisory (AV25-819)

Serial number: AV25-819
Date: December 11, 2025

On December 9, 2025, Mozilla published security advisories to address vulnerabilities in the following products:

  • Firefox – versions prior to 146
  • Firefox ESR – versions prior to 115.31
  • Firefox ESR – versions prior to 140.6
  • Thunderbird – versions prior to 146
  • Thunderbird – versions prior to 140.6

The Cyber Centre encourages users and administrators to review the provided web links and apply the necessary updates.

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