CVE-2026-16375

CriticalCVSS 9.8

Published: 21/07/2026(UTC)Updated: 24/07/2026(UTC)Translated: 24/07/2026(UTC)NVD NIST

Exploitation Probability (EPSS)

Low risk

0.22%

13th percentile - higher than 13% of all known CVEs

Summary

Site isolation vulnerability in the HTTP networking component of Firefox. This issue was fixed in Firefox 153, Firefox ESR 140.13, Thunderbird 153, and Thunderbird 140.13.

Risk Assessment

An attacker could exploit this flaw to bypass site isolation, potentially leading to data leakage or cross-site attacks.

Recommendation

Immediately update Firefox and Thunderbird to the latest versions.

Original NVD description (English source)

Site isolation issue in the Networking: HTTP component. This vulnerability was fixed in Firefox 153, Firefox ESR 140.13, Thunderbird 153, and Thunderbird 140.13.