CVE-2026-2763
CriticalPublished
Use-after-free in the JavaScript Engine component
- Published
- Feb 24, 2026
- Updated
- Jul 15, 2026
- Assigning CNA
- mozilla
- Evidence observed
- Aug 25, 2026
Primary CVSS
9.8/ 10Critical
nvd · CVSS 3.1
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H0.5%
Low · next 30 days
- Percentile
- 39.7%
- Model date
- Sep 21, 2026
EPSS is a statistical estimate, not a certainty or a measure of impact. Combine it with CVSS, KEV status, exposure and your environment.
Summary
Use-after-free in the JavaScript Engine component. This vulnerability was fixed in Firefox 148, Firefox ESR 115.33, Firefox ESR 140.8, Thunderbird 148, and Thunderbird 140.8.
Sources
1Proof-of-concept exploit for CVE-2026-2763, a use-after-free in Mozilla's JavaScript engine, demonstrating a constrained 1-bit write primitive leading to out-of-bounds read/write.
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