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CVE-2026-4702JIT miscompilation in the JavaScript Engine component
- 9.8CriticalCVSS base score
- 0.72%Exploitation in 30 daysEPSS · top 46% of all CVEs
- NoKnown exploitednot in CISA's KEV catalog
- NonePublic exploitsnone known yet
Description
JIT miscompilation in the JavaScript Engine component. This vulnerability was fixed in Firefox 149, Firefox ESR 140.9, Thunderbird 149, and Thunderbird 140.9.
Timeline
ID reserved
By mozilla
- 1 day later
· 1 day later
Published
- 20 days later
· 20 days later
Record updated
Changes after publication (a new score, a public exploit, EPSS crossing 1, 10 or 50 %, leaving KEV) are kept since November 2026; earlier ones are not known.
Scores
| Scored by | CVSS | Score | Vector |
|---|---|---|---|
| CISA-ADPADP (enrichment) | 3.1 | Critical9.8 | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H |
| NVDNVD · Modified | 3.1 | Critical9.8 | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H |
- EPSS (exploitation in 30 days)
- 0.72% · top 46% of all CVEs (12 Nov 2026)
- CISA SSVC
- Exploitation: none · Automatable: yes · Technical impact: total
Loading the EPSS history…
The list uses the assigner's score when there is one, then CISA's, then NVD's: Critical 9.8.
Affected products
- unaffected 140.9 – ≤ 140.*
- unaffected 149 – ≤ *
- unaffected 140.9 – ≤ 140.*
- unaffected 149 – ≤ *
References
References5
- https://bugzilla.mozilla.org/show_bug.cgi?id=2013560 (opens in a new tab)
- https://www.mozilla.org/security/advisories/mfsa2026-20/ (opens in a new tab)
- https://www.mozilla.org/security/advisories/mfsa2026-22/ (opens in a new tab)
- https://www.mozilla.org/security/advisories/mfsa2026-23/ (opens in a new tab)
- https://www.mozilla.org/security/advisories/mfsa2026-24/ (opens in a new tab)
Sources
The same CVE in the primary databases and aggregators, to check against.
- CVE.org record (opens in a new tab)
- CVE List JSON (GitHub) (opens in a new tab)
- NVD (opens in a new tab)
- FIRST EPSS (opens in a new tab)
- EUVD EUVD-2026-14821 (opens in a new tab)
- OSV.dev (opens in a new tab)
- GitHub Advisories (opens in a new tab)
- CIRCL Vulnerability-Lookup (opens in a new tab)
Badge for a README or a ticket
[](https://cveledger.app/cve/CVE-2026-4702)Record last updated .