CVE-2026-109723

Deferred Deferred - Pending Action

Integer Overflow in Firefox Layout Text and Fonts Component

Publication date: 2026-10-13

Last updated on: 2026-10-15

Assigner: Mozilla Corporation

Description

Integer overflow in the Layout: Text and Fonts component. This vulnerability was fixed in Firefox 158, 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-2026-109723

EUVD

EUVD-2026-98493

Affected Vendors & Products

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

Helpful Resources

Exploitability

CWE

KEV

CWE ID	Description
CWE-190	The product performs a calculation that can produce an integer overflow or wraparound when the logic assumes that the resulting value will always be larger than the original value. This occurs when an integer value is incremented to a value that is too large to store in the associated representation. When this occurs, the value may become a very small or negative number.

Attack-Flow Graph

Executive Summary

This vulnerability is an integer overflow in the Layout: Text and Fonts component of Firefox and Firefox ESR. An integer overflow occurs when a calculation produces a result larger than the maximum value that can be stored in the variable's data type, potentially leading to unexpected behavior or crashes.

Detection Guidance

This vulnerability is an integer overflow in Firefox's Layout: Text and Fonts component, fixed in versions Firefox 158, Firefox ESR 153.5, Thunderbird 158, and Thunderbird 153.5. To detect it, check your installed Firefox or Thunderbird version using commands like 'firefox --version' or 'thunderbird --version'. If the version is below the fixed releases, the system is vulnerable.

Impact Analysis

This vulnerability could allow attackers to execute arbitrary code or cause denial-of-service conditions by exploiting the integer overflow in text and font handling. Users running vulnerable versions of Firefox or Firefox ESR may experience crashes or system compromise.

Compliance Impact

The provided CVE data does not specify how this vulnerability impacts compliance with standards like GDPR or HIPAA. The description only mentions an integer overflow in the Layout: Text and Fonts component fixed in Firefox 158 and Firefox ESR 153.5.

Mitigation Strategies

Update Firefox to version 158 or later and Firefox ESR to version 153.5 or later to address the integer overflow in the Layout: Text and Fonts component.

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