Mikhail Oblozhikhin

**Name of the Vulnerable Software and Affected Versions** Mozilla Firefox versions prior to 79 Mozilla Firefox ESR versions prior to 78.1 Thunderbird versions prior to 78.1 **Description** The issue is related to information leakage in error messages. It allows a remote attacker to disclose protected information by observing the stack trace for JavaScript errors in web workers, specifically when content can be parsed as script. **Recommendations** For Mozilla Firefox versions prior to 79, update to version 79 or later to resolve the issue. For Mozilla Firefox ESR versions prior to 78.1, update to version 78.1 or later to resolve the issue. For Thunderbird versions prior to 78.1, update to version 78.1 or later to resolve the issue.