CVE-2026-0884: Use-after-free in the JavaScript Engine component
Use-after-free in the JavaScript Engine component. This vulnerability affects Firefox < 147 and Firefox ESR < 140.7.
Other sources
Use-after-free in the JavaScript Engine component. This vulnerability was fixed in Firefox 147, Firefox ESR 140.7, Thunderbird 147, and Thunderbird 140.7.
— Ubuntu
Affected Software
Remediation
Recommended actions to resolve this vulnerability, in priority order.
- Upgrade
Upgrade to a fixed release to a version that resolves this vulnerability.
Fixed in 147 - Upgrade
Upgrade
ubuntu/thunderbirdto a version that resolves this vulnerability.Fixed in 1:140.7.1+build1-0ubuntu0.22.04.1 - Upgrade
Upgrade to a fixed release to a version that resolves this vulnerability.
Fixed in 140.7 - Upgrade
Upgrade
debian/firefoxto a version that resolves this vulnerability.Fixed in 160.0-1 - Upgrade
Upgrade
debian/firefox-esrto a version that resolves this vulnerability.Fixed in 140.12.0esr-1~deb12u1Fixed in 153.7.0esr-1~deb12u1Fixed in 140.15.0esr-1~deb13u1Fixed in 153.6.0esr-1~deb13u1Fixed in 153.5.1esr-1Fixed in 153.7.0esr-1 - Upgrade
Upgrade
debian/thunderbirdto a version that resolves this vulnerability.Fixed in 1:140.12.0esr-1~deb12u1Fixed in 1:153.6.0esr-1~deb12u2Fixed in 1:140.12.0esr-1~deb13u1Fixed in 1:153.6.0esr-1~deb13u1Fixed in 1:153.5.0esr-1Fixed in 1:153.7.0esr-1 - Upgrade
Upgrade
Firefoxto a version that resolves this vulnerability.Fixed in 147 - Upgrade
Upgrade
Firefox ESRto a version that resolves this vulnerability.Fixed in 140.7 - Upgrade
Upgrade
Thunderbirdto a version that resolves this vulnerability.Fixed in 147 - Upgrade
Upgrade
Thunderbirdto a version that resolves this vulnerability.Fixed in 140.7
Event History
Parent advisories
This vulnerability appears in the following advisories.
Peer vulnerabilities
Found alongside the following vulnerabilities.
Frequently Asked Questions
What is the severity of CVE-2026-0884?
CVE-2026-0884 is classified as a critical vulnerability due to its potential to allow remote code execution.
How do I fix CVE-2026-0884?
To address CVE-2026-0884, update Firefox to version 147 or Firefox ESR to version 140.7 or later.
What versions of Firefox are affected by CVE-2026-0884?
CVE-2026-0884 affects Firefox versions prior to 147 and Firefox ESR versions prior to 140.7.
What does the term 'use-after-free' mean in the context of CVE-2026-0884?
'Use-after-free' refers to a vulnerability where a program continues to use memory that has already been freed, potentially leading to arbitrary code execution.
Is there a workaround for CVE-2026-0884?
There is no known workaround for CVE-2026-0884; the recommended action is to apply the necessary updates.