CVE-2026-0884
published 2026-01-13CVE-2026-0884: 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.
PriorityP351critical9.8CVSS 3.1
AVNACLPRNUINSUCHIHAH
EPSS
0.42%
34.3th percentile
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.
Affected
12 ranges
| Vendor | Product | Version range | Fixed in |
|---|---|---|---|
| debian | firefox | < firefox 147.0-1 (sid) | firefox 147.0-1 (sid) |
| debian | firefox-esr | < firefox 147.0-1 (sid) | firefox 147.0-1 (sid) |
| debian | thunderbird | < firefox 147.0-1 (sid) | firefox 147.0-1 (sid) |
| mozilla | firefox | < 140.7.0 | 140.7.0 |
| mozilla | firefox | < 147.0 | 147.0 |
| mozilla | firefox | — | — |
| mozilla | thunderbird | < 140.7.0 | 140.7.0 |
| mozilla | thunderbird | < 147.0 | 147.0 |
| mozilla | thunderbird | >= 0 < 1:140.7.0esr-1~deb11u1 | 1:140.7.0esr-1~deb11u1 |
| mozilla | thunderbird | >= 0 < 1:140.7.0esr-1~deb12u1 | 1:140.7.0esr-1~deb12u1 |
| mozilla | thunderbird | >= 0 < 1:140.7.0esr-1~deb13u1 | 1:140.7.0esr-1~deb13u1 |
| mozilla | thunderbird | >= 0 < 1:140.7.0esr-1 | 1:140.7.0esr-1 |
CVSS provenance
nvdv3.19.8CRITICALCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
osv9.8CRITICAL
vendor_debian9.8CRITICAL
vendor_redhat9.8CRITICAL
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Ubuntu
Thunderbird vulnerabilities
vendor_ubuntu·2026-02-02
CVE-2025-8031 Thunderbird vulnerabilities
Title: Thunderbird vulnerabilities
Summary: Several security issues were fixed in Thunderbird.
Multiple security issues were discovered in Thunderbird. If a user were
tricked into opening a specially crafted website in a browsing context,
an attacker could potentially exploit these to cause a denial of service,
obtain sensitive information, bypass security restrictions, cross-site
tracing, or execute arbitrary code.
Instructions: In general, a standard system update will make all the necessary changes.
Red Hat
firefox: thunderbird: Use-after-free in the JavaScript Engine component
vendor_redhat·2026-01-13·CVSS 9.8
CVE-2026-0884 [CRITICAL] firefox: thunderbird: Use-after-free in the JavaScript Engine component
firefox: thunderbird: Use-after-free in the JavaScript Engine component
Use-after-free in the JavaScript Engine component. This vulnerability affects Firefox < 147, Firefox ESR < 140.7, Thunderbird < 147, and Thunderbird < 140.7.
A flaw was found in Firefox and Thunderbird. The Mozilla Foundation's Security Advisory describes the following issue:
Use-after-free in the JavaScript Engine component
Statement: Red Hat Product Security rates the severity of this flaw as determined by the Mozilla Foundation Security Advisory.
Package: rhel10/firefox-flatpak (Red Hat Enterprise Linux 10) - Affected
Package: rhel10/thunderbird-flatpak (Red Hat Enterprise Linux 10) - Affected
Package: firefox (Red Hat Enterprise Linux 6) - Out of support scope
Package: thunderbird (Red Hat Enterprise Linux 6
Debian
CVE-2026-0884: firefox - Use-after-free in the JavaScript Engine component. This vulnerability affects Fi...
vendor_debian·2026·CVSS 9.8
CVE-2026-0884 [CRITICAL] CVE-2026-0884: firefox - Use-after-free in the JavaScript Engine component. This vulnerability affects Fi...
Use-after-free in the JavaScript Engine component. This vulnerability affects Firefox < 147, Firefox ESR < 140.7, Thunderbird < 147, and Thunderbird < 140.7.
Scope: local
sid: resolved (fixed in 147.0-1)
Mozilla
Mozilla Foundation Security Advisory 2026-04: CVE-2026-0884
vendor_mozilla·CVSS 9.8
CVE-2026-0884 [CRITICAL] Mozilla Foundation Security Advisory 2026-04: CVE-2026-0884
Mozilla Foundation Security Advisory 2026-04
CVE: CVE-2026-0884
Product: Thunderbird
Impact: moderate
Fixed in: Thunderbird 147
Mozilla
Mozilla Foundation Security Advisory 2026-03: CVE-2026-0884
vendor_mozilla·CVSS 9.8
CVE-2026-0884 [CRITICAL] Mozilla Foundation Security Advisory 2026-03: CVE-2026-0884
Mozilla Foundation Security Advisory 2026-03
CVE: CVE-2026-0884
Product: Firefox ESR
Impact: high
Fixed in: Firefox ESR 140.7
Mozilla
Mozilla Foundation Security Advisory 2026-05: CVE-2026-0884
vendor_mozilla·CVSS 9.8
CVE-2026-0884 [CRITICAL] Mozilla Foundation Security Advisory 2026-05: CVE-2026-0884
Mozilla Foundation Security Advisory 2026-05
CVE: CVE-2026-0884
Product: Thunderbird
Impact: high
Fixed in: Thunderbird 140.7
Mozilla
Mozilla Foundation Security Advisory 2026-01: CVE-2026-0884
vendor_mozilla·CVSS 9.8
CVE-2026-0884 [CRITICAL] Mozilla Foundation Security Advisory 2026-01: CVE-2026-0884
Mozilla Foundation Security Advisory 2026-01
CVE: CVE-2026-0884
Product: Firefox
Impact: moderate
Fixed in: Firefox 147
GHSA
GHSA-jmj2-8j2p-hmq6: Use-after-free in the JavaScript Engine component
ghsa_unreviewed·2026-01-13
CVE-2026-0884 [CRITICAL] CWE-416 GHSA-jmj2-8j2p-hmq6: 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.
OSV
CVE-2026-0884: Use-after-free in the JavaScript Engine component
osv·2026-01-13·CVSS 9.8
CVE-2026-0884 [CRITICAL] CVE-2026-0884: Use-after-free in the JavaScript Engine component
Use-after-free in the JavaScript Engine component. This vulnerability affects Firefox < 147, Firefox ESR < 140.7, Thunderbird < 147, and Thunderbird < 140.7.
No detection rules found.
No public exploits indexed.
Wiz
CVE-2026-0884 Impact, Exploitability, and Mitigation Steps | Wiz
blogs_wiz·CVSS 9.8
CVE-2026-0884 [CRITICAL] CVE-2026-0884 Impact, Exploitability, and Mitigation Steps | Wiz
## CVE-2026-0884 :
NixOS vulnerability analysis and mitigation
Use-after-free in the JavaScript Engine component. This vulnerability affects Firefox < 147, Firefox ESR < 140.7, Thunderbird < 147, and Thunderbird < 140.7.
Source : NVD
## 9.8
Score
Published January 13, 2026
Severity CRITICAL
CNA Score 9.8
Affected Technologies
NixOS
Mozilla Firefox
Has Public Exploit No
Has CISA KEV Exploit No
CISA KEV Release Date N/A
CISA KEV Due Date N/A
Exploitation Probability Percentile (EPSS) 7.1
Exploitation Probability (EPSS) N/A
Affected packages and libraries
rhel10::firefox-flatpak.src
rhel10::thunderbird-flatpak
Sources
AlmaLinux 8 Severity HIGH Has Fix Added at: Feb 11, 2026
AlmaLinux 9 Severity HIGH Has Fix Added at: Jan 20, 2026
Debian 11, 12, 13, 14 Severity CRITIC
Bugzilla
CVE-2026-0884 firefox: thunderbird: Use-after-free in the JavaScript Engine component
bugzilla·2026-01-13·CVSS 9.8
CVE-2026-0884 [CRITICAL] CVE-2026-0884 firefox: thunderbird: Use-after-free in the JavaScript Engine component
CVE-2026-0884 firefox: thunderbird: 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.
Discussion:
This issue has been addressed in the following products:
Red Hat Enterprise Linux 8
Via RHSA-2026:0667 https://access.redhat.com/errata/RHSA-2026:0667
---
This issue has been addressed in the following products:
Red Hat Enterprise Linux 9
Via RHSA-2026:0694 https://access.redhat.com/errata/RHSA-2026:0694
---
This issue has been addressed in the following products:
Red Hat Enterprise Linux 9
Via RHSA-2026:0924 https://access.redhat.com/errata/RHSA-2026:0924
---
This issue has been addressed in the following products:
Red Hat Enterprise Linux 9.6 Extended Update Su
2026-01-13
Published