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Critical · 9.8 CVE-2026-4729 EUVD-2026-14873GHSA-xh4v-qr89-3hj3

Memory safety bugs fixed in Firefox 149 and Thunderbird 149

Published Mar 24, 2026 · Updated Jul 15, 2026 · Assigned by mozilla

Description

Memory safety bugs present in Firefox 148 and Thunderbird 148. 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 149 and Thunderbird 149.

Affected products

VendorProductAffectedFixed
Mozilla Firefox — 149
Mozilla Thunderbird — 149

Fixed in Linux distributions

Distributions backport fixes, so the version that fixes this vulnerability differs per release — upgrade to at least the version shown. From the distributions' security trackers and advisories.

ReleasePackageFixed inAdvisory
Ubuntu 24.04 LTS mozjs102 +1 No fix yet —
Ubuntu 22.04 LTS mozjs78 +3 No fix yet —
Ubuntu 20.04 LTS mozjs52 +1 No fix yet —
Ubuntu 18.04 LTS mozjs38 +1 No fix yet —
ReleasePackageFixed inAdvisory
openSUSE Tumbleweed MozillaFirefox 149.0-1.1 openSUSE-SU-2026:10458-1
openSUSE Tumbleweed firefox-esr 153.0-1.1 openSUSE-SU-2026:11373-1

Wolfi

ReleasePackageFixed inAdvisory
Wolfi rolling firefox 149.0-r0 —

Advisories 4

References