CVE-2026-100765

Undergoing Analysis Undergoing Analysis - In Progress

Use-after-free in Firefox JavaScript WebAssembly

Publication date: 2026-09-29

Last updated on: 2026-10-13

Assigner: Mozilla Corporation

Description

Use-after-free in the JavaScript: WebAssembly component. This vulnerability was fixed in Firefox ESR 153.4, Thunderbird 157, Thunderbird 153.4, and Firefox 157.

CVSS Scores

EPSS Scores

Probability:
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Meta Information

Published

2026-09-29

Last Modified

2026-10-13

Generated

2026-10-19

AI Q&A

2026-09-29

EPSS Evaluated

2026-10-18

NVD

CVE-2026-100765

EUVD

EUVD-2026-88917

Affected Vendors & Products

Vendor	Product	Version / Range
mozilla	firefox	to 153.4.0 (exc)
mozilla	firefox	From 154.0.0 (inc) to 157.0.0 (exc)
mozilla	thunderbird	to 153.4.0 (exc)
mozilla	thunderbird	From 154.0 (inc) to 157.0 (exc)

Helpful Resources

Exploitability

CWE

KEV

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 Any operations using the original pointer are no longer valid because the memory "belongs" to the code that operates on the new pointer.

Attack-Flow Graph

Executive Summary

This vulnerability is a use-after-free issue in the JavaScript WebAssembly component of Firefox. Use-after-free means a program tries to use memory after it has been freed, which can lead to crashes or arbitrary code execution. It was fixed in Firefox ESR 153.4 and Firefox 157.

Detection Guidance

This vulnerability is specific to Firefox's JavaScript and WebAssembly components. Detection requires checking Firefox version and inspecting for use-after-free patterns in WebAssembly execution. No direct network detection commands are available. Verify Firefox version with 'firefox --version' and ensure it is 157 or higher for Firefox or 153.4 or higher for Firefox ESR.

Impact Analysis

This vulnerability could allow attackers to execute arbitrary code or crash the browser by exploiting the use-after-free flaw in the WebAssembly component. Users running vulnerable versions of Firefox may be at risk of remote code execution or denial-of-service attacks.

Compliance Impact

The provided CVE data does not specify direct impacts on compliance with GDPR, HIPAA, or other standards. The vulnerability involves a use-after-free in JavaScript: WebAssembly, which could lead to arbitrary code execution or memory corruption. Such issues may indirectly affect compliance by compromising data integrity or confidentiality, but no explicit details are provided.

Mitigation Strategies

Update Firefox ESR to version 153.4 or Firefox to version 157 or later to address the use-after-free vulnerability in the JavaScript: WebAssembly component.

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