JIT Miscompilation in Firefox's JavaScript Engine by Mozilla
CVE-2026-109733

8.1HIGH

Key Information:

Vendor

Mozilla
Status
Firefox
Thunderbird
Vendor
CVE Published:
13 October 2026

What is CVE-2026-109733?

A vulnerability exists in the Just-In-Time (JIT) compilation component of Firefox's JavaScript Engine, which can lead to unexpected behaviors or potential exploits. This issue has been addressed and patched in Firefox versions 158, Firefox ESR 115.43, and Firefox ESR 153.5. Users are advised to update to these versions to ensure their systems remain secure against this type of vulnerability.

Affected Version(s)

Firefox 115.43

Firefox 153.5

Firefox 158

References

https://bugzilla.mozilla.org/show_bug.cgi?id=2076269
https://www.mozilla.org/security/advisories/mfsa2026-106/
https://www.mozilla.org/security/advisories/mfsa2026-107/

CVSS V3.1

Score:
8.1
Severity:
HIGH
Confidentiality:
High
Integrity:
High
Availability:
High
Attack Vector:
Network
Attack Complexity:
Low
Privileges Required:
None
User Interaction:
Required
Scope:
Unchanged

Timeline

  • Vulnerability published

  • Vulnerability Reserved

Credit

Amy Burnett of OpenAI
.