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HIGH

Memory safety bugs fixed in Firefox ESR 140.10, Thunderbird ESR 140.10, Firefox 150 and Thunderbird 150

Published Apr 21, 2026

Description

Memory safety bugs present in Firefox ESR 140.9, Thunderbird ESR 140.9, Firefox 149 and Thunderbird 149. Some of these bugs showed evidence of memory corruption and we presume that with enough effort some of these could have been exploited to run arbitrary code. This vulnerability was fixed in Firefox 150, Firefox ESR 140.10, Thunderbird 150, and Thunderbird 140.10.

Affected products

Remediation

Red Hat statement

Red Hat Product Security rates the severity of this flaw as determined by the Mozilla Foundation Security Advisory.

Weaknesses (3)

CWE-125

Out-of-bounds Read

CWE-416

Use After Free

CWE-787

Out-of-bounds Write

References (40)

Change history (0)

No recorded changes yet.

Sources

CVE.org / MITRE

Status PUBLISHED
Assigner mozilla
Published Apr 21, 2026
Updated Jul 15, 2026
Reserved Apr 21, 2026
Link CVE-2026-6786

CISA Vulnrichment

Updated Apr 22, 2026

NVD

Status Modified
Modified Jul 15, 2026
Link CVE-2026-6786

Red Hat

Severity Important
Public date Apr 21, 2026
Bugzilla 2460088
Link CVE-2026-6786

ENISA EUVD

Assigner mozilla
Published Apr 21, 2026
Updated Jul 15, 2026
Link EUVD-2026-24127

GitHub

No data