CVE-2026-109707
Deferred Deferred - Pending Action

Networking Component Use-After-Free Sandbox Escape in Firefox

Publication date: 2026-10-13

Last updated on: 2026-10-13

Assigner: Mozilla Corporation

Description
Sandbox escape due to use-after-free in the Networking component. This vulnerability was fixed in Firefox 158, Firefox ESR 153.5, Thunderbird 158, and Thunderbird 153.5.

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Meta Information

Published
2026-10-13
Last Modified
2026-10-13
Generated
2026-10-19
AI Q&A
2026-10-13
EPSS Evaluated
2026-10-18
NVD
CVE-2026-109707
EUVD
EUVD-2026-98484

Affected Vendors & Products

Showing 2 associated CPEs
Vendor Product Version / Range
mozilla firefox 158
mozilla firefox_esr 153.5

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 Any operations using the original pointer are no longer valid because the memory "belongs" to the code that operates on the new pointer.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 Networking component of Firefox. A use-after-free occurs when a program continues to use memory after it has been freed, potentially allowing an attacker to execute arbitrary code outside the sandbox. The issue was patched in Firefox 158 and Firefox ESR 153.5.

Detection Guidance

This vulnerability is a sandbox escape in Firefox's Networking component due to a use-after-free issue. Detection requires checking Firefox version and monitoring for suspicious activity. Update Firefox to version 158 or later to patch the vulnerability.

Impact Analysis

If exploited, this vulnerability could allow an attacker to break out of the browser's sandbox and run malicious code on your system with the same privileges as the browser. This could lead to unauthorized access to sensitive data, installation of malware, or further compromise of your device.

Compliance Impact

This vulnerability allows sandbox escape and arbitrary code execution, which could lead to unauthorized access to sensitive data. Such access could violate GDPR's data protection requirements and HIPAA's safeguards for protected health information if exploited in systems handling regulated data.

Mitigation Strategies

Update Firefox to version 158 or later and Firefox ESR to version 153.5 or later to address the use-after-free vulnerability in the Networking component.

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