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CVE-2026-2778 Details

Description

Sandbox escape due to incorrect boundary conditions in the DOM: Core & HTML component. This vulnerability was fixed in Firefox 148, Firefox ESR 115.33, Firefox ESR 140.8, Thunderbird 148, and Thunderbird 140.8.

Metrics

CVSS 3.x Severity and Vector Strings:

NIST: [email protected]CVSS-B:10 CRITICALVector:CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H

CNA: redhat-SADPCVSS-B:7.5 HIGHVector:CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:H

References to Advisories, Solutions, and Tools

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URL	Source(s)	Tag(s)
https://access.redhat.com/errata/RHSA-2026:3338	redhat-SADP
https://access.redhat.com/errata/RHSA-2026:3339	redhat-SADP
https://access.redhat.com/errata/RHSA-2026:3361	redhat-SADP
https://access.redhat.com/errata/RHSA-2026:3491	redhat-SADP
https://access.redhat.com/errata/RHSA-2026:3492	redhat-SADP
https://access.redhat.com/errata/RHSA-2026:3493	redhat-SADP
https://access.redhat.com/errata/RHSA-2026:3494	redhat-SADP
https://access.redhat.com/errata/RHSA-2026:3495	redhat-SADP
https://access.redhat.com/errata/RHSA-2026:3496	redhat-SADP
https://access.redhat.com/errata/RHSA-2026:3497	redhat-SADP
https://access.redhat.com/errata/RHSA-2026:3515	redhat-SADP
https://access.redhat.com/errata/RHSA-2026:3516	redhat-SADP
https://access.redhat.com/errata/RHSA-2026:3517	redhat-SADP
https://access.redhat.com/errata/RHSA-2026:3976	redhat-SADP
https://access.redhat.com/errata/RHSA-2026:3978	redhat-SADP
https://access.redhat.com/errata/RHSA-2026:3979	redhat-SADP
https://access.redhat.com/errata/RHSA-2026:3980	redhat-SADP
https://access.redhat.com/errata/RHSA-2026:3981	redhat-SADP
https://access.redhat.com/errata/RHSA-2026:3982	redhat-SADP
https://access.redhat.com/errata/RHSA-2026:3983	redhat-SADP
https://access.redhat.com/errata/RHSA-2026:3984	redhat-SADP
https://access.redhat.com/errata/RHSA-2026:4022	redhat-SADP
https://access.redhat.com/errata/RHSA-2026:4152	redhat-SADP
https://access.redhat.com/errata/RHSA-2026:4260	redhat-SADP
https://access.redhat.com/errata/RHSA-2026:4432	redhat-SADP
https://access.redhat.com/security/cve/CVE-2026-2778	redhat-SADP
https://bugzilla.redhat.com/show_bug.cgi?id=2442335	redhat-SADP
https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-2778.json	redhat-SADP
https://bugzilla.mozilla.org/show_bug.cgi?id=2016358	[email protected]	Issue TrackingPermissions Required
https://www.mozilla.org/security/advisories/mfsa2026-13/	[email protected]	Vendor Advisory
https://www.mozilla.org/security/advisories/mfsa2026-14/	[email protected]	Vendor Advisory
https://www.mozilla.org/security/advisories/mfsa2026-15/	[email protected]	Vendor Advisory
https://www.mozilla.org/security/advisories/mfsa2026-16/	[email protected]	Vendor Advisory
https://www.mozilla.org/security/advisories/mfsa2026-17/	[email protected]	Vendor Advisory

see all 34 references

Weakness Enumeration

CWE-ID	CWE Name	Source
NVD-CWE-noinfo	Insufficient Information to Classify Weakness	[email protected]
CWE-119	Improper Restriction of Operations within the Bounds of a Memory Buffer	CISA-ADP

Affected Products

Product	Versions
mozilla firefox	< 115.33.0 < 148.0 >= 128.0, < 140.8.0
CPE cpe:2.3:a:mozilla:firefox:::::esr:::* cpe:2.3:a:mozilla:firefox:::::-:::* Remediation No remediation found in references.
mozilla thunderbird	< 140.8.0 < 148.0
CPE cpe:2.3:a:mozilla:thunderbird:::::esr:::* cpe:2.3:a:mozilla:thunderbird:::::-:::* Remediation No remediation found in references.

Change History

9 change records found show changes

Date	Action	Recorded By
Jul 15, 2026	CVE Modified	redhat-SADP
Jun 30, 2026	CVE Modified	redhat-SADP
Jun 17, 2026	CVE Modified	[email protected]
Jun 17, 2026	CVE Modified	CISA-ADP
Apr 13, 2026	CVE Modified	[email protected]
Feb 28, 2026	CVE Modified	CISA-ADP
Feb 25, 2026	Initial Analysis	[email protected]
Feb 24, 2026	CVE Modified	[email protected]
Feb 24, 2026	New CVE Received	[email protected]