CVE-2026-92021 Firefox ESR - Use After Free

Firefox ESR < 140.16 contains a use-after-free vulnerability caused by improper memory handling in the JavaScript Engine JIT component, letting attackers cause memory corruption or remote code execution, exploit requires crafted web content.

CVSS base score 8.8 /10
High
CISA KEV
Not listed
Public exploit
None known
Authentication
Not required
EPSS
0.28% chance of exploitation in 30 days
View the NVD record ↗

Details

Type
Use After Free
Impact
Remote Code Execution
CVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
Published
15 September 2026
Updated
15 October 2026
Weakness
CWE-416

Vendor fix

Update to Firefox ESR 140.16 or later.

Patching closes this CVE. It does not tell you which of your systems run the affected version, or what else is exposed alongside them.

References

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