CVE-2026-8391: Vulnerability in Mozilla Firefox
CVE-2026-8391 is a high-impact vulnerability in the JavaScript Engine component of Mozilla Firefox. It was addressed and fixed in Firefox version 150. 0. 3 as part of a security update announced on May 12, 2026. The vulnerability is one of several issues resolved in this release, all related to the JavaScript Engine, including JIT and WebAssembly components. No known exploits in the wild have been reported. The vendor advisory confirms the fix and recommends updating to the patched version.
AI Analysis
Technical Summary
CVE-2026-8391 is a vulnerability categorized as 'other issue' within the JavaScript Engine component of Mozilla Firefox. It was reported by researcher ggwhyp and assigned high impact by Mozilla. The issue was fixed in Firefox 150.0.3, which addresses multiple high-impact vulnerabilities in the JavaScript Engine, including JIT miscompilation and use-after-free bugs. The vendor advisory (MFSA 2026-45) provides official confirmation of the fix and references the relevant bug report (Bug 2038575). No CVSS score is available for this vulnerability.
Potential Impact
The vulnerability has been rated as high impact by Mozilla, indicating it could potentially allow significant security issues if exploited. However, no known exploits in the wild have been reported. The impact specifics are not detailed beyond the high rating, but it affects the JavaScript Engine, a critical component of Firefox's execution environment.
Mitigation Recommendations
Mozilla has released Firefox 150.0.3 which includes the fix for CVE-2026-8391. Users and administrators should update to this version or later to remediate the vulnerability. Since this is a client-side application, patching the browser is the primary and effective mitigation. No additional mitigations are specified or required by the vendor.
CVE-2026-8391: Vulnerability in Mozilla Firefox
Description
CVE-2026-8391 is a high-impact vulnerability in the JavaScript Engine component of Mozilla Firefox. It was addressed and fixed in Firefox version 150. 0. 3 as part of a security update announced on May 12, 2026. The vulnerability is one of several issues resolved in this release, all related to the JavaScript Engine, including JIT and WebAssembly components. No known exploits in the wild have been reported. The vendor advisory confirms the fix and recommends updating to the patched version.
AI-Powered Analysis
Machine-generated threat intelligence
Technical Analysis
CVE-2026-8391 is a vulnerability categorized as 'other issue' within the JavaScript Engine component of Mozilla Firefox. It was reported by researcher ggwhyp and assigned high impact by Mozilla. The issue was fixed in Firefox 150.0.3, which addresses multiple high-impact vulnerabilities in the JavaScript Engine, including JIT miscompilation and use-after-free bugs. The vendor advisory (MFSA 2026-45) provides official confirmation of the fix and references the relevant bug report (Bug 2038575). No CVSS score is available for this vulnerability.
Potential Impact
The vulnerability has been rated as high impact by Mozilla, indicating it could potentially allow significant security issues if exploited. However, no known exploits in the wild have been reported. The impact specifics are not detailed beyond the high rating, but it affects the JavaScript Engine, a critical component of Firefox's execution environment.
Mitigation Recommendations
Mozilla has released Firefox 150.0.3 which includes the fix for CVE-2026-8391. Users and administrators should update to this version or later to remediate the vulnerability. Since this is a client-side application, patching the browser is the primary and effective mitigation. No additional mitigations are specified or required by the vendor.
Technical Details
- Data Version
- 5.2
- Assigner Short Name
- mozilla
- Date Reserved
- 2026-05-12T12:36:14.816Z
- Cvss Version
- null
- State
- PUBLISHED
- Remediation Level
- null
- Vendor Advisory Urls
- [{"url":"https://www.mozilla.org/security/advisories/mfsa2026-45/","vendor":"Mozilla"}]
Threat ID: 6a032959cbff5d8610e85ad6
Added to database: 5/12/2026, 1:21:29 PM
Last enriched: 5/12/2026, 1:37:17 PM
Last updated: 5/12/2026, 10:42:25 PM
Views: 63
Community Reviews
0 reviewsCrowdsource mitigation strategies, share intel context, and vote on the most helpful responses. Sign in to add your voice and help keep defenders ahead.
Want to contribute mitigation steps or threat intel context? Sign in or create an account to join the community discussion.
Actions
Updates to AI analysis require Pro Console access. Upgrade inside Console → Billing.
Need more coverage?
Upgrade to Pro Console for AI refresh and higher limits.
For incident response and remediation, OffSeq services can help resolve threats faster.
Latest Threats
Check if your credentials are on the dark web
Instant breach scanning across billions of leaked records. Free tier available.