CVE-2026-12296
CRITICALCVSS 9.6/10EPSS 0.30%
Last modified
CVE-2026-12296 is a critical-severity vulnerability rated 9.6/10 on the CVSS scale. Sandbox escape in the Security: Process Sandboxing component. This vulnerability was fixed in Firefox 152, Firefox ESR 140.12, Thunderbird 152, and Thunderbird 140.12.. EPSS estimates a 0.30% chance of exploitation in the next 30 days.
Description
Sandbox escape in the Security: Process Sandboxing component. This vulnerability was fixed in Firefox 152, Firefox ESR 140.12, Thunderbird 152, and Thunderbird 140.12.
Metrics
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:H/A:H
Weakness Enumeration
Affected Software
| Vendor | Product | Versions |
|---|---|---|
| Mozilla | Firefox | < 140.12.0 |
| Mozilla | Firefox | < 152.0.0 |
| Mozilla | Thunderbird | < 140.12.0 |
| Mozilla | Thunderbird | < 152.0.0 |
References
- https://bugzilla.mozilla.org/show_bug.cgi?id=2040515Permissions Required
- https://www.mozilla.org/security/advisories/mfsa2026-57/Vendor Advisory
- https://www.mozilla.org/security/advisories/mfsa2026-58/Vendor Advisory
- https://www.mozilla.org/security/advisories/mfsa2026-60/Vendor Advisory
- https://www.mozilla.org/security/advisories/mfsa2026-61/Vendor Advisory
Timeline
- Published
- Last Modified
- Status
- Analyzed
Frequently Asked Questions
What is CVE-2026-12296?
Sandbox escape in the Security: Process Sandboxing component. This vulnerability was fixed in Firefox 152, Firefox ESR 140.12, Thunderbird 152, and Thunderbird 140.12.
How severe is CVE-2026-12296?
CVE-2026-12296 has a CVSS score of 9.6/10 (CRITICAL severity). The EPSS model estimates a 0.30% probability of exploitation in the next 30 days.
How do I fix CVE-2026-12296?
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.
Are you affected by CVE-2026-12296?
Run a free Strix scan to check your systems for this vulnerability.
Scan your code nowSource: NVD / NIST