CVE-2026-4687
HIGHCVSS 8.6/10EPSS 0.43%
Last modified
CVE-2026-4687 is a high-severity vulnerability rated 8.6/10 on the CVSS scale. Sandbox escape due to incorrect boundary conditions in the Telemetry component. This vulnerability was fixed in Firefox 149, Firefox ESR 115.34, Firefox ESR 140.9, Thunderbird 149, and Thunderbird 140.9.. EPSS estimates a 0.43% chance of exploitation in the next 30 days.
Description
Sandbox escape due to incorrect boundary conditions in the Telemetry component. This vulnerability was fixed in Firefox 149, Firefox ESR 115.34, Firefox ESR 140.9, Thunderbird 149, and Thunderbird 140.9.
Metrics
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:H
Weakness Enumeration
Affected Software
| Vendor | Product | Versions |
|---|---|---|
| Mozilla | Firefox | < 115.34.0 |
| Mozilla | Firefox | < 149.0 |
| Mozilla | Firefox | >= 128.0, < 140.9.0 |
References
- https://bugzilla.mozilla.org/show_bug.cgi?id=2016368Permissions Required
- https://www.mozilla.org/security/advisories/mfsa2026-20/Vendor Advisory
- https://www.mozilla.org/security/advisories/mfsa2026-21/Vendor Advisory
- https://www.mozilla.org/security/advisories/mfsa2026-22/Vendor Advisory
Timeline
- Published
- Last Modified
- Status
- Modified
Frequently Asked Questions
What is CVE-2026-4687?
Sandbox escape due to incorrect boundary conditions in the Telemetry component. This vulnerability was fixed in Firefox 149, Firefox ESR 115.34, Firefox ESR 140.9, Thunderbird 149, and Thunderbird 140.9.
How severe is CVE-2026-4687?
CVE-2026-4687 has a CVSS score of 8.6/10 (HIGH severity). The EPSS model estimates a 0.43% probability of exploitation in the next 30 days.
How do I fix CVE-2026-4687?
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-2026-4687?
Run a free Strix scan to check your systems for this vulnerability.
Scan your code nowSource: NVD / NIST