CVE-2024-5691: Mozilla Firefox

Medium severity, CVSS 4.7. EPSS: 0.7% chance of exploitation in the next 30 days.

By tricking the browser with a `X-Frame-Options` header, a sandboxed iframe could have presented a button that, if clicked by a user, would bypass restrictions to open a new window. This vulnerability affects Firefox < 127, Firefox ESR < 115.12, and Thunderbird < 115.12.

Affected products

• Mozilla Firefox: before 127.0 (fixed in 127.0)
• Mozilla Firefox ESR: before 115.12 (fixed in 115.12)
• Mozilla Thunderbird: before 115.12 (fixed in 115.12)

Published 2024-06-11. Last modified 2026-06-17.