Integer overflow in the Networking: JAR component. This vulnerability was fixed in Firefox 151, Firefox ESR 140.11, Thunderbird 151, and Thunderbird 140.11.

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
  • Thunderbird

Configuration 1 [-]

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

No data.

References
Link Providers
https://bugzilla.mozilla.org/show_bug.cgi?id=2032427 cve-icon cve-icon
https://nvd.nist.gov/vuln/detail/CVE-2026-8956 cve-icon
https://www.cve.org/CVERecord?id=CVE-2026-8956 cve-icon
https://www.mozilla.org/security/advisories/mfsa2026-46/ cve-icon cve-icon
https://www.mozilla.org/security/advisories/mfsa2026-48/ cve-icon cve-icon
https://www.mozilla.org/security/advisories/mfsa2026-48/#CVE-2026-8956 cve-icon
https://www.mozilla.org/security/advisories/mfsa2026-50/ cve-icon cve-icon
https://www.mozilla.org/security/advisories/mfsa2026-51/ cve-icon cve-icon
History

Fri, 22 May 2026 00:15:00 +0000

Type Values Removed Values Added
References
Metrics threat_severity

None

 threat_severity

Moderate

Wed, 20 May 2026 14:45:00 +0000

Type Values Removed Values Added
First Time appeared Mozilla thunderbird
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:*:*:*
Vendors & Products Mozilla thunderbird

Tue, 19 May 2026 20:15:00 +0000

Type Values Removed Values Added
Weaknesses CWE-680

Tue, 19 May 2026 17:45:00 +0000

Type Values Removed Values Added
Description Integer overflow in the Networking: JAR component. This vulnerability was fixed in Firefox 151 and Firefox ESR 140.11. Integer overflow in the Networking: JAR component. This vulnerability was fixed in Firefox 151, Firefox ESR 140.11, Thunderbird 151, and Thunderbird 140.11.
References

Tue, 19 May 2026 17:30:00 +0000

Type Values Removed Values Added
Weaknesses CWE-190
Metrics 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'}

ssvc

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

Tue, 19 May 2026 16:00:00 +0000

Type Values Removed Values Added
Weaknesses CWE-680

Tue, 19 May 2026 15:15:00 +0000

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

Tue, 19 May 2026 13:45:00 +0000

Type Values Removed Values Added
Description Integer overflow in the Networking: JAR component. This vulnerability was fixed in Firefox 151 and Firefox ESR 140.11.
Title Integer overflow in the Networking: JAR component
References
cve-icon MITRE

Status: PUBLISHED

Assigner: mozilla

Published: 2026-05-19T12:29:51.114Z

Updated: 2026-05-19T17:10:49.476Z

Reserved: 2026-05-19T12:29:50.365Z

Link: CVE-2026-8956

cve-icon Vulnrichment

Updated: 2026-05-19T16:39:14.659Z

cve-icon NVD

Status : Analyzed

Published: 2026-05-19T14:16:51.943

Modified: 2026-05-20T14:31:07.807

Link: CVE-2026-8956

cve-icon Redhat

Severity : Moderate

Publid Date: 2026-05-19T12:29:51Z

Links: CVE-2026-8956 - Bugzilla