CVE-2026-100780

Analyzed Analyzed - Analysis Complete

Use-after-free in Firefox ESR and Firefox

Publication date: 2026-09-29

Last updated on: 2026-10-05

Assigner: Mozilla Corporation

Description

Use-after-free in the DOM: Core & HTML component. This vulnerability was fixed in Firefox ESR 153.4, Thunderbird 157, Thunderbird 140.17, Thunderbird 153.4, Firefox 157, Firefox ESR 115.42, and Firefox ESR 140.17.

CVSS Scores

EPSS Scores

Probability:
Percentile:

Meta Information

Published

2026-09-29

Last Modified

2026-10-05

Generated

2026-10-19

AI Q&A

2026-09-29

EPSS Evaluated

2026-10-18

NVD

CVE-2026-100780

EUVD

EUVD-2026-88932

Affected Vendors & Products

Vendor	Product	Version / Range
mozilla	firefox	to 157.0.0 (exc)
mozilla	thunderbird	to 157.0 (exc)
mozilla	firefox	From 115.1.0 (inc) to 115.42.0 (exc)
mozilla	firefox	From 140.0 (inc) to 140.17.0 (exc)
mozilla	firefox	From 153.0 (inc) to 153.4.0 (exc)
mozilla	thunderbird	From 140.0 (inc) to 140.17.0 (exc)
mozilla	thunderbird	From 153.0 (inc) to 153.4.0 (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 Any operations using the original pointer are no longer valid because the memory "belongs" to the code that operates on the new pointer.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 is a use-after-free vulnerability in the DOM: Core & HTML component of Firefox. Use-after-free occurs when a program continues to use memory after it has been freed, potentially leading to crashes or arbitrary code execution.

Detection Guidance

This vulnerability is specific to Firefox browsers and requires checking the installed version. Use commands like 'firefox --version' or 'about:support' in Firefox to verify if your version is below the patched releases (Firefox ESR 153.4, Firefox 157, Firefox ESR 115.42, Firefox ESR 140.17).

Impact Analysis

An attacker could exploit this to crash the browser or run malicious code on your system. This may allow unauthorized access to sensitive data or control of your device.

Compliance Impact

The provided CVE data does not specify how this vulnerability impacts compliance with standards like GDPR or HIPAA. Without additional context on data exposure or processing implications, its effect on compliance cannot be determined.

Mitigation Strategies

Update Firefox ESR to version 153.4 or later, Firefox to version 157 or later, or Firefox ESR to version 115.42 or later, or Firefox ESR to version 140.17 or later.

Hi! I’m here to help you understand CVE-2026-100780. Ask me anything about the vulnerability, its impact, or mitigation strategies.

0/70