Privilege escalation in the Messaging System component. This vulnerability affects Firefox < 148, Firefox ESR < 115.33, Firefox ESR < 140.8, Thunderbird < 148, and Thunderbird < 140.8.

Metrics

No CVSS v4.0

Attack Vector Network

Attack Complexity Low

Privileges Required None

Scope Unchanged

Confidentiality Impact High

Integrity Impact High

Availability Impact High

User Interaction None

No CVSS v3.0

No CVSS v2

This CVE is not in the KEV list.

Exploitation none

Automatable yes

Technical Impact total

Affected Vendors & Products

Vendors Products
Mozilla
  • Firefox
  • Firefox Esr
  • Thunderbird

Configuration 1 [-]

OR cpe:2.3:a:mozilla:firefox:*:*:*:*:esr:*:*:*
cpe:2.3:a:mozilla:firefox:*:*:*:*:-:*:*:*
cpe:2.3:a:mozilla:firefox:*:*:*:*:esr:*:*:*
cpe:2.3:a:mozilla:thunderbird:*:*:*:*:esr:*:*:*
cpe:2.3:a:mozilla:thunderbird:*:*:*:*:-:*:*:*

No data.

References
Link Providers
https://www.spirityenterprise.com/virtual-ciso spirity
https://bugzilla.mozilla.org/show_bug.cgi?id=2015305 cve-icon cve-icon
https://nvd.nist.gov/vuln/detail/CVE-2026-2777 cve-icon
https://www.cve.org/CVERecord?id=CVE-2026-2777 cve-icon
https://www.mozilla.org/security/advisories/mfsa2026-13/ cve-icon cve-icon
https://www.mozilla.org/security/advisories/mfsa2026-14/ cve-icon cve-icon
https://www.mozilla.org/security/advisories/mfsa2026-15/ cve-icon cve-icon
https://www.mozilla.org/security/advisories/mfsa2026-15/#CVE-2026-2777 cve-icon
https://www.mozilla.org/security/advisories/mfsa2026-16/ cve-icon cve-icon
https://www.mozilla.org/security/advisories/mfsa2026-17/ cve-icon cve-icon
History

Wed, 25 Feb 2026 19:15:00 +0000

Type Values Removed Values Added
Weaknesses CWE-269
Metrics ssvc

{'options': {'Automatable': 'yes', 'Exploitation': 'none', 'Technical Impact': 'total'}, 'version': '2.0.3'}

Wed, 25 Feb 2026 16:30:00 +0000

Type Values Removed Values Added
Weaknesses NVD-CWE-noinfo
CPEs cpe:2.3:a:mozilla:firefox:*:*:*:*:-:*:*:*
cpe:2.3:a:mozilla:firefox:*:*:*:*:esr:*:*:*
cpe:2.3:a:mozilla:thunderbird:*:*:*:*:-:*:*:*
cpe:2.3:a:mozilla:thunderbird:*:*:*:*:esr:*:*:*
Metrics cvssV3_1

{'score': 7.5, 'vector': 'CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:H'}

 cvssV3_1

{'score': 9.8, 'vector': 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H'}

Wed, 25 Feb 2026 12:00:00 +0000

Type Values Removed Values Added
First Time appeared Mozilla
Mozilla firefox
Mozilla firefox Esr
Mozilla thunderbird
Vendors & Products Mozilla
Mozilla firefox
Mozilla firefox Esr
Mozilla thunderbird

Wed, 25 Feb 2026 00:15:00 +0000

Type Values Removed Values Added
References
Metrics threat_severity

None

 cvssV3_1

{'score': 7.5, 'vector': 'CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:H'}

threat_severity

Important

Tue, 24 Feb 2026 18:00:00 +0000

Type Values Removed Values Added
Description Privilege escalation in the Messaging System component. This vulnerability affects Firefox < 148, Firefox ESR < 115.33, and Firefox ESR < 140.8. Privilege escalation in the Messaging System component. This vulnerability affects Firefox < 148, Firefox ESR < 115.33, Firefox ESR < 140.8, Thunderbird < 148, and Thunderbird < 140.8.
References

Tue, 24 Feb 2026 14:00:00 +0000

Type Values Removed Values Added
Description Privilege escalation in the Messaging System component. This vulnerability affects Firefox < 148, Firefox ESR < 115.33, and Firefox ESR < 140.8.
Title Privilege escalation in the Messaging System component
References
cve-icon MITRE

Status: PUBLISHED

Assigner: mozilla

Published:

Updated: 2026-02-25T17:46:32.467Z

Reserved: 2026-02-19T15:06:03.824Z

Link: CVE-2026-2777

cve-icon Vulnrichment

Updated: 2026-02-25T17:46:27.061Z

cve-icon NVD

Status : Modified

Published: 2026-02-24T14:16:26.123

Modified: 2026-02-25T19:43:24.020

Link: CVE-2026-2777

cve-icon Redhat

Severity : Important

Publid Date: 2026-02-24T13:33:12Z

Links: CVE-2026-2777 - Bugzilla