CVE-2026-8391

Other issue in the JavaScript Engine component

CVSS 5.3 MEDIUMEPSS 0.2%CWE-119 CWE-20 CWE-79

Vexday Risk Score

13Low

SSVC decision (CISA)

Track

No exploitation signal → monitor

CVSS 5.3EPSS 0.2%KEV nãoPoC —Nuclei —Metasploit —Patch —

Lifecycle

12 May 2026Published on NVD

Recommendation: Monitor — no exploitation signal at the moment.

Other issue in the JavaScript Engine component. This vulnerability was fixed in Firefox 150.0.3, Firefox ESR 115.36, Firefox ESR 140.11, and Thunderbird 140.11.

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

Affected products

Mozilla · Firefox Mozilla · Thunderbird

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References

https://bugzilla.mozilla.org/show_bug.cgi?id=2038575 https://www.mozilla.org/security/advisories/mfsa2026-45/https://www.mozilla.org/security/advisories/mfsa2026-47/https://www.mozilla.org/security/advisories/mfsa2026-48/https://www.mozilla.org/security/advisories/mfsa2026-51/