CVE-2026-74939

Privilege escalation in the DOM: Navigation component. This vulnerability was fixed in Firefox 154, Firefox ESR 115.39, Firefox ESR 140.14, Firefox ESR 153.1, Thunderbird 154, Thunderbird 140.14, and Thunderbird 153.1.

CVSS v3.1

8.8 HIGHCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H

EPSS

0.30% chance of exploitation in the next 30 days, 23th percentile

Published

2026-08-18

Updated

2026-08-21

Proof-of-concept exploits (1)

• SneakyNachos/CVE-2026-74939-escape-the-mac-n-cheese-box1★ · 2026-08-24

References

• CVE Record
• NVD entry

Related

• CVE-2024-29943
• CVE-2026-12295
• CVE-2026-15718
• CVE-2026-2764
• CVE-2026-2766
• CVE-2026-4692