CVE-2026-74963

Name of the Vulnerable Software and Affected Versions Firefox versions prior to 154 Firefox ESR versions prior to 140.14 Firefox ESR versions prior to 153.1 Thunderbird versions prior to 154 Thunderbird ESR versions prior to 140.14 Thunderbird ESR versions prior to 153.1

Description A same-origin policy bypass exists in the Networking: Cookies component. The same-origin policy is a critical security mechanism that restricts how a document or script loaded from one origin can interact with a resource from another origin.

Recommendations Update Firefox to version 154. Update Firefox ESR to version 140.14. Update Firefox ESR to version 153.1. Update Thunderbird to version 154. Update Thunderbird ESR to version 140.14. Update Thunderbird ESR to version 153.1.