CVE-2026-4700

CriticalCVSS 9.8

Published: 24/03/2026(UTC)Updated: 15/07/2026(UTC)Translated: 16/07/2026(UTC)NVD NIST

Exploitation Probability (EPSS)

Low risk

0.46%

37th percentile - higher than 37% of all known CVEs

Summary

A mitigation bypass vulnerability exists in the Networking: HTTP component of Firefox and Thunderbird. The flaw was fixed in Firefox 149, Firefox ESR 140.9, Thunderbird 149, and Thunderbird 140.9.

Risk Assessment

Bypassing HTTP security mechanisms could allow an attacker to intercept or modify network traffic, compromising the confidentiality and integrity of user data.

Recommendation

Immediately update Firefox to version 149 or later, and Thunderbird to version 149 or 140.9 to remediate the vulnerability.

Original NVD description (English source)

Mitigation bypass in the Networking: HTTP component. This vulnerability was fixed in Firefox 149, Firefox ESR 140.9, Thunderbird 149, and Thunderbird 140.9.