CVE-2026-4696: Use-after-free in the Layout: Text and Fonts component

Published Mar 24, 2026
·
Updated

Use-after-free in the Layout: Text and Fonts component. This vulnerability affects Firefox < 149, Firefox ESR < 115.34, and Firefox ESR < 140.9.

Other sources

Use-after-free in the Layout: Text and Fonts component. This vulnerability was fixed in Firefox 149, Firefox ESR 115.34, Firefox ESR 140.9, Thunderbird 149, and Thunderbird 140.9.

MITRE

Affected Software

10 affected componentsFixes available
Mozilla Firefox<149
Mozilla Firefox ESR<115.34, <140.9
Mozilla Firefox<149
149
Mozilla Firefox ESR<115.34
115.34
Mozilla Firefox ESR<140.9
140.9
Mozilla Firefox<115.34.0
Mozilla Firefox<149.0
Mozilla Firefox>=128.0<140.9.0
Mozilla Thunderbird<140.9
140.9
Mozilla Thunderbird<149
149

Event History

Mar 24, 2026
CVE Published
via Mozilla·12:00 AM
Data Sourced
via Mozilla·12:00 AM
DescriptionSeverityAffected Software
Updated
via Mozilla·12:00 AM
Affected Software
CVE Published
via MITRE·12:30 PM
Data Sourced
via MITRE·12:30 PM
Description
Data Sourced
via Red Hat·01:03 PM
DescriptionSeverityAffected Software
Data Sourced
via NVD·01:16 PM
DescriptionSeverityWeaknessAffected Software
Apr 7, 58249
Event
via FIRST·08:52 AM

Parent advisories

This vulnerability appears in the following advisories.

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Frequently Asked Questions

1

What is the severity of CVE-2026-4696?

CVE-2026-4696 has been classified as a critical vulnerability due to the potential for remote code execution.

2

How do I fix CVE-2026-4696?

To fix CVE-2026-4696, update to Firefox version 149, Firefox ESR version 115.34 or 140.9, or Thunderbird version 149 or 140.9.

3

Which versions are affected by CVE-2026-4696?

CVE-2026-4696 affects Firefox versions less than 149, Firefox ESR versions less than 115.34 and 140.9, and Thunderbird versions less than 149 and 140.9.

4

What types of software are impacted by CVE-2026-4696?

CVE-2026-4696 impacts multiple versions of Firefox, Firefox ESR, and Thunderbird.

5

Is there any workaround for CVE-2026-4696?

There are no known workarounds for CVE-2026-4696; the recommended approach is to update to the patched versions.

Contact

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