CVE-2026-16375
CRITICALCVSS 9.8/10EPSS 0.22%
Last modified
CVE-2026-16375 is a critical-severity vulnerability rated 9.8/10 on the CVSS scale. 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.. EPSS estimates a 0.22% chance of exploitation in the next 30 days.
Description
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.
Metrics
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Weakness Enumeration
Affected Software
| Vendor | Product | Versions |
|---|---|---|
| Mozilla | Firefox | < 140.13.0 |
| Mozilla | Firefox | < 153.0.0 |
| Mozilla | Thunderbird | < 140.13.0 |
| Mozilla | Thunderbird | >= 141.0, < 153.0 |
References
- https://bugzilla.mozilla.org/show_bug.cgi?id=2032140Permissions Required
- https://www.mozilla.org/security/advisories/mfsa2026-68/Vendor Advisory
- https://www.mozilla.org/security/advisories/mfsa2026-70/Vendor Advisory
- https://www.mozilla.org/security/advisories/mfsa2026-71/Vendor Advisory
- https://www.mozilla.org/security/advisories/mfsa2026-72/Vendor Advisory
Timeline
- Published
- Last Modified
- Status
- Analyzed
Frequently Asked Questions
What is CVE-2026-16375?
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.
How severe is CVE-2026-16375?
CVE-2026-16375 has a CVSS score of 9.8/10 (CRITICAL severity). The EPSS model estimates a 0.22% probability of exploitation in the next 30 days.
How do I fix CVE-2026-16375?
Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.
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Are you affected by CVE-2026-16375?
Run a free Strix scan to check your systems for this vulnerability.
Scan your code nowSource: NVD / NIST