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Vulnerability record · CVE-2026-2776 · published 24 February 2026

CVE-2026-2776: Mozilla firefox memory buffer overflow vulnerability

Mozilla · Firefox

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.

10.0 CVSS 3.1 Critical EPSS 0.61% · top 52.7% CWE-119 · Memory buffer overflow
10.0CVSS 3.1 base score
0.61%EPSS exploitation probability, 30 days
NoNot in CISA KEV
2Affected product versions listed by NVD
34References
15 Jul 2026Last modified by NVD

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/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H

Affected products

2 vulnerable configurations from NVD's CPE data, grouped by vendor and product.

References

LinkTags
https://bugzilla.mozilla.org/show_bug.cgi?id=2015266 Issue TrackingPermissions 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
https://access.redhat.com/errata/RHSA-2026:4432
https://access.redhat.com/security/cve/CVE-2026-2776
https://bugzilla.redhat.com/show_bug.cgi?id=2442291
https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-2776.json

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Related vulnerabilities

Same products first, then exploited flaws of the same weakness class.

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Source: NIST National Vulnerability Database (record CVE-2026-2776), CISA KEV, FIRST EPSS (scores of 2026-09-26). This page is refreshed as NVD updates the record.