CVE-2026-8391: Other issue in the JavaScript Engine component
Published May 12, 2026
·Updated
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 Software
6 affected componentsFixes available
Mozilla Firefox<150.0.3
Mozilla Firefox<150.0.3
150.0.3
Mozilla Firefox ESR<115.36
115.36
Mozilla Firefox ESR<140.11
140.11
Mozilla Firefox<150.0.3
Mozilla Thunderbird<140.11
140.11
Event History
May 12, 2026
CVE Published
via Mozilla·12:00 AM
Data Sourced
via Mozilla·12:00 AM
DescriptionSeverityAffected Software
CVE Published
via MITRE·12:36 PM
Data Sourced
via MITRE·12:36 PM
Description
Data Sourced
via NVD·02:17 PM
DescriptionSeverityWeaknessAffected Software
May 19, 2026
Updated
via Mozilla·12:00 AM
Affected Software
Apr 22, 58353
Event
via FIRST·12:01 PM
Frequently Asked Questions
1
What is the severity of CVE-2026-8391?
CVE-2026-8391 is considered to be a high severity vulnerability due to its potential impact on the JavaScript Engine in Mozilla Firefox.
2
How do I fix CVE-2026-8391?
To fix CVE-2026-8391, users should update Mozilla Firefox to version 150.0.3 or later.
3
What components are affected by CVE-2026-8391?
CVE-2026-8391 affects the JavaScript Engine component of Mozilla Firefox.
4
Was CVE-2026-8391 exploited in the wild?
There is no public information indicating that CVE-2026-8391 has been exploited in the wild.
5
What versions of Firefox are vulnerable to CVE-2026-8391?
Firefox versions prior to 150.0.3 are vulnerable to CVE-2026-8391.