What’s Vulnerable › Vulnerabilities

CVE-2026-8391: Other issue in the JavaScript Engine component

• Severity: medium (CVSS 5.3 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.3% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2026-05-12 · updated 2026-10-25
• Weakness: CWE-20

Description

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.

Affected products

• Mozilla Firefox: before 150.0.3 — fixed in 150.0.3

How to fix

Upgrade to a fixed version: Mozilla Firefox 150.0.3. Check the vendor advisory for mitigations.

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/
• https://access.redhat.com/errata/RHSA-2026:21378
• https://access.redhat.com/errata/RHSA-2026:21380
• https://access.redhat.com/errata/RHSA-2026:21381
• https://access.redhat.com/errata/RHSA-2026:21382
• https://access.redhat.com/errata/RHSA-2026:22325
• https://access.redhat.com/errata/RHSA-2026:22643
• https://access.redhat.com/errata/RHSA-2026:26174

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