CVE-2026-92040
Received Received - Intake

Use-after-free in Firefox JavaScript WebAssembly

Publication date: 2026-09-15

Last updated on: 2026-10-05

Assigner: Mozilla Corporation

Description
Use-after-free in the JavaScript: WebAssembly component. This vulnerability was fixed in Firefox 156 and Thunderbird 156.

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Meta Information

Published
2026-09-15
Last Modified
2026-10-05
Generated
2026-10-05
AI Q&A
2026-09-15
EPSS Evaluated
2026-10-04
NVD
CVE-2026-92040
EUVD
EUVD-2026-78503

Affected Vendors & Products

Showing 2 associated CPEs
Vendor Product Version / Range
mozilla firefox to 156.0.0 (exc)
mozilla thunderbird to 156.0 (exc)

Helpful Resources

Exploitability

CWE
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KEV
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CWE ID Description
CWE-416 The product reuses or references memory after it has been freed. At some point afterward, the memory may be allocated again and saved in another pointer, while the original pointer references a location somewhere within the new allocation. Any operations using the original pointer are no longer valid because the memory "belongs" to the code that operates on the new pointer.

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Executive Summary

This is a use-after-free vulnerability in the JavaScript WebAssembly component of Firefox. Use-after-free means the software tries to use memory after it has been freed, which can lead to crashes or arbitrary code execution.

Detection Guidance

This vulnerability is specific to Firefox versions before 156. Detection involves checking the installed Firefox version. Use commands like 'firefox --version' or 'apt show firefox' (for Debian-based systems) to verify the version. If the version is below 156, the system is vulnerable.

Impact Analysis

An attacker could exploit this to execute arbitrary code on your system, potentially allowing them to install malware, steal data, or take control of your device. It may also cause Firefox to crash repeatedly.

Mitigation Strategies

Update Firefox to version 156 or later to address the use-after-free vulnerability in the JavaScript: WebAssembly component.

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