CVE-2026-109753

Deferred Deferred - Pending Action

Layout Component Boundary Condition Flaw in Firefox

Publication date: 2026-10-13

Last updated on: 2026-10-15

Assigner: Mozilla Corporation

Description

Incorrect boundary conditions in the Layout component. This vulnerability was fixed in Firefox 158, Firefox ESR 115.43, Firefox ESR 153.5, Thunderbird 158, and Thunderbird 153.5.

CVSS Scores

EPSS Scores

Probability:
Percentile:

Meta Information

Published

2026-10-13

Last Modified

2026-10-15

Generated

2026-10-19

AI Q&A

2026-10-13

EPSS Evaluated

2026-10-18

NVD

CVE-2026-109753

EUVD

EUVD-2026-98651

Affected Vendors & Products

Vendor	Product	Version / Range
mozilla	firefox	to 158 (inc)
mozilla	firefox_esr	to 115.43 (inc)
mozilla	firefox_esr	to 153.5 (inc)

Helpful Resources

Exploitability

CWE

KEV

CWE ID	Description
CWE-119	The product performs operations on a memory buffer, but it reads from or writes to a memory location outside the buffer's intended boundary. This may result in read or write operations on unexpected memory locations that could be linked to other variables, data structures, or internal program data.

Attack-Flow Graph

Executive Summary

This vulnerability involves incorrect boundary conditions in Firefox's Layout component. It was patched in Firefox 158 and specific Firefox ESR versions (115.43 and 153.5). The issue likely allows improper handling of layout rendering, potentially leading to unexpected behavior or crashes.

Detection Guidance

This vulnerability is specific to Firefox and Firefox ESR versions before 158, 115.43, and 153.5 respectively. Detection involves checking installed versions of Firefox or Firefox ESR on your system. Use commands like 'firefox --version' or 'firefox-esr --version' to verify versions. If the version is below the patched release, the system is vulnerable.

Impact Analysis

The vulnerability could cause Firefox to crash or behave unpredictably during webpage rendering. Users might experience freezes, incorrect page layouts, or denial-of-service conditions if exploited maliciously.

Mitigation Strategies

Update Firefox to version 158 or later, Firefox ESR to version 115.43 or later, or Firefox ESR to version 153.5 or later to address the incorrect boundary conditions in the Layout component.

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