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Vulnerability IntelligenceCVE-2026-2766

CVE-2026-2766

CRITICAL9.8

Use-after-free in the JavaScript Engine: JIT component

Published Feb 24, 2026

Modified 5 days ago

Fix available

Details

Use-after-free in the JavaScript Engine: JIT component. This vulnerability affects Firefox < 148, Firefox ESR < 140.8, Thunderbird < 148, and Thunderbird < 140.8.

Affected Packages

Firefox

Ubuntu 14.04 LTSUbuntu 16.04 LTSUbuntu 18.04 LTSUbuntu 20.04 LTSUbuntu 22.04 LTS

Fixed in:

148

Mozilla Firefox

Windows 10 (1507)Windows 10 (1607) / Server 2016Windows 10 (1809) / Server 2019Windows 10 (1903)Windows 10 (1909)

Fixed in:

148

Mozilla Firefox ESR

Windows 10 (1507)Windows 10 (1607) / Server 2016Windows 10 (1809) / Server 2019Windows 10 (1903)Windows 10 (1909)

Fixed in:

140.8

Firefox ESR

macOS 14macOS 15macOS 26

Fixed in:

140.8

References

WEB

https://bugzilla.mozilla.org/show_bug.cgi?id=2013583

ADVISORY

https://www.cve.org/CVERecord?id=CVE-2026-2766

WEB

https://www.mozilla.org/security/advisories/mfsa2026-13/

WEB

https://www.mozilla.org/security/advisories/mfsa2026-15/

WEB

https://www.mozilla.org/security/advisories/mfsa2026-16/

WEB

https://www.mozilla.org/security/advisories/mfsa2026-17/

CVSS Analysis

CVSS v3.1

9.8

Exploitability

Attack Vector

NetworkAV:N

Attack Complexity

LowAC:L

Privileges Required

NonePR:N

User Interaction

NoneUI:N

Scope

UnchangedS:U

Impact

Confidentiality

HighC:H

Integrity

HighI:H

Availability

HighA:H

9.8/CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Ecosystems(28)

Ubuntu 14.04 LTS Ubuntu 16.04 LTS Ubuntu 18.04 LTS Ubuntu 20.04 LTS Ubuntu 22.04 LTS

Timeline

PublishedFeb 24, 2026

ModifiedFeb 28, 2026

CVE-2026-2766 | Mondoo Vulnerability Intelligence