VulnerabilityModified
CVE-2026-2776
This vulnerability was fixed in Firefox 148, Firefox ESR 115.33, Firefox ESR 140.8, Thunderbird 148, and Thunderbird 140.8.
CRITICAL 10.0EPSS 0.48%
Does this matter?
High impact if exploited, but EPSS currently rates exploitation as unlikely (0.48%). Schedule it in the normal patch cycle and watch for a rise in EPSS or a public exploit.
Description
Sandbox escape due to incorrect boundary conditions in the Telemetry component in External Software. This vulnerability was fixed in Firefox 148, Firefox ESR 115.33, Firefox ESR 140.8, Thunderbird 148, and Thunderbird 140.8.
- CVSS 3.1
- 10.0 CRITICALCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H
- EPSS
- 0.48% probability · 40th percentile
- CISA KEV
- Not listed
- Weakness
- CWE-119
- Affected
- mozilla/firefox · mozilla/thunderbird
- Source
- security@mozilla.org
References
- https://bugzilla.mozilla.org/show_bug.cgi?id=2015266Issue Tracking, Permissions Required
- https://www.mozilla.org/security/advisories/mfsa2026-13/Vendor Advisory
- https://www.mozilla.org/security/advisories/mfsa2026-14/Vendor Advisory
- https://www.mozilla.org/security/advisories/mfsa2026-15/Vendor Advisory
- https://www.mozilla.org/security/advisories/mfsa2026-16/Vendor Advisory
- https://www.mozilla.org/security/advisories/mfsa2026-17/Vendor Advisory
- https://access.redhat.com/errata/RHSA-2026:3338
- https://access.redhat.com/errata/RHSA-2026:3339
- https://access.redhat.com/errata/RHSA-2026:3361
- https://access.redhat.com/errata/RHSA-2026:3491
- https://access.redhat.com/errata/RHSA-2026:3492
- https://access.redhat.com/errata/RHSA-2026:3493
- https://access.redhat.com/errata/RHSA-2026:3494
- https://access.redhat.com/errata/RHSA-2026:3495
- https://access.redhat.com/errata/RHSA-2026:3496
- https://access.redhat.com/errata/RHSA-2026:3497
- https://access.redhat.com/errata/RHSA-2026:3515
- https://access.redhat.com/errata/RHSA-2026:3516
- https://access.redhat.com/errata/RHSA-2026:3517
- https://access.redhat.com/errata/RHSA-2026:3976
- https://access.redhat.com/errata/RHSA-2026:3978
- https://access.redhat.com/errata/RHSA-2026:3979
- https://access.redhat.com/errata/RHSA-2026:3980
- https://access.redhat.com/errata/RHSA-2026:3981
- https://access.redhat.com/errata/RHSA-2026:3982
- https://access.redhat.com/errata/RHSA-2026:3983
- https://access.redhat.com/errata/RHSA-2026:3984
- https://access.redhat.com/errata/RHSA-2026:4022
- https://access.redhat.com/errata/RHSA-2026:4152
- https://access.redhat.com/errata/RHSA-2026:4260
Source: NVD record, EPSS from FIRST.org, KEV from CISA. Refreshed daily.