CVE-2026-100818
Received Received - Intake

Widget: Gtk Use-After-Free Sandbox Escape in Firefox

Publication date: 2026-09-29

Last updated on: 2026-09-29

Assigner: Mozilla Corporation

Description
Sandbox escape due to use-after-free in the Widget: Gtk component. This vulnerability was fixed in Firefox ESR 153.4, Firefox 157, and Firefox ESR 140.17.

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Meta Information

Published
2026-09-29
Last Modified
2026-09-29
Generated
2026-09-29
AI Q&A
2026-09-29
EPSS Evaluated
N/A
NVD
CVE-2026-100818
EUVD
EUVD-2026-88797

Affected Vendors & Products

Showing 4 associated CPEs
Vendor Product Version / Range
mozilla firefox to 153.4 (inc)
mozilla firefox 157
mozilla firefox 140.17
mozilla firefox 153.4

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 Any operations using the original pointer are no longer valid because the memory "belongs" to the code that operates on the new pointer.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 sandbox escape vulnerability caused by a use-after-free error in the Widget: Gtk component of Firefox. A use-after-free occurs when a program continues to use memory after it has been freed, potentially allowing malicious code to execute outside the sandboxed environment.

Detection Guidance

This vulnerability is a sandbox escape in Firefox's Widget: Gtk component due to a use-after-free issue. Detection primarily involves checking Firefox version and applying patches. No specific network or system commands are provided in the context to detect this vulnerability directly.

Impact Analysis

This vulnerability could allow an attacker to break out of the browser's sandbox and execute arbitrary code on your system with the same privileges as the Firefox process. This could lead to unauthorized access to sensitive data, installation of malware, or further compromise of your system.

Compliance Impact

The vulnerability allows sandbox escape and potential arbitrary code execution, which could lead to unauthorized data access or modification. This may impact compliance with GDPR (data protection) and HIPAA (health data security) by increasing risks of data breaches or unauthorized processing.

Mitigation Strategies

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

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