Vulnerability · Published Sep 1, 2026 · Assigned by mozilla
CVE-2026-84122Use-after-free in the Audio/Video component
Medium 5.4
In plain English
A medium-severity use-after-free in Firefox from Mozilla. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.2% (higher than 12% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.
Severity (CVSS 3.1)5.4Medium
Exploit odds (30 days)0.2%top 88.2% of all CVEs
Exploited in the wildNo reportsCISA SSVC: none
Attack toolingNoneno public tooling known
Official description
Use-after-free in the Audio/Video component. This vulnerability was fixed in Firefox 155, Firefox ESR 140.15, Firefox ESR 153.2, Thunderbird 155, Thunderbird 140.15, and Thunderbird 153.2.
Affected packages & fixed versions
| Ecosystem | Package | Fixed in | Advisory |
|---|---|---|---|
| AlmaLinux:10 | firefox | 140.15.0-1.el10_2 | ALSA-2026:67129 |
| AlmaLinux:8 | firefox | 140.15.0-1.el8_10.alma.1 | ALSA-2026:68549 |
| AlmaLinux:9 | firefox | 140.15.0-1.el9_8.alma.1 | ALSA-2026:67133 |
| AlmaLinux:9 | firefox-x11 | 140.15.0-1.el9_8.alma.1 | ALSA-2026:67133 |
| AlmaLinux:10 | thunderbird | 140.16.0-1.el10_2.alma.1 | ALSA-2026:73130 |
| AlmaLinux:8 | thunderbird | 140.16.0-1.el8_10.alma.1 | ALSA-2026:73971 |
| AlmaLinux:9 | thunderbird | 140.16.0-1.el9_8.alma.1 | ALSA-2026:70642 |
| Debian:12 | firefox-esr | 140.15.0esr-1~deb12u1 | DEBIAN-CVE-2026-84122 |
| Debian:13 | firefox-esr | 140.15.0esr-1~deb13u1 | DEBIAN-CVE-2026-84122 |
| Debian:14 | firefox-esr | 140.15.0esr-1 | DEBIAN-CVE-2026-84122 |
| Debian:12 | thunderbird | 1:140.15.0esr-1~deb12u1 | DEBIAN-CVE-2026-84122 |
| Debian:13 | thunderbird | 1:140.15.0esr-1~deb13u1 | DEBIAN-CVE-2026-84122 |
| Debian:14 | thunderbird | 1:153.2.0esr-1 | DEBIAN-CVE-2026-84122 |
| Rocky Linux:10 | firefox | 0:140.15.0-1.el10_2 | RLSA-2026:67129 |
| Rocky Linux:8 | firefox | 0:140.15.0-1.el8_10 | RLSA-2026:68549 |
| Rocky Linux:9 | firefox | 0:140.15.0-1.el9_8 | RLSA-2026:67133 |
| Rocky Linux:10 | thunderbird | 0:140.16.0-1.el10_2 | RLSA-2026:73130 |
| Rocky Linux:8 | thunderbird | 0:140.16.0-1.el8_10 | RLSA-2026:73971 |
| Rocky Linux:9 | thunderbird | 0:140.16.0-1.el9_8 | RLSA-2026:70642 |
| Ubuntu:22.04:LTS | mozjs102 | no fix listed | UBUNTU-CVE-2026-84122 |
| Ubuntu:24.04:LTS | mozjs102 | no fix listed | UBUNTU-CVE-2026-84122 |
| Ubuntu:24.04:LTS | mozjs115 | no fix listed | UBUNTU-CVE-2026-84122 |
| Ubuntu:22.04:LTS | mozjs78 | no fix listed | UBUNTU-CVE-2026-84122 |
| Ubuntu:22.04:LTS | mozjs91 | no fix listed | UBUNTU-CVE-2026-84122 |
| Ubuntu:22.04:LTS | thunderbird | no fix listed | UBUNTU-CVE-2026-84122 |
Affected products (as reported)
| Vendor | Product | Versions |
|---|---|---|
| Mozilla | Firefox | see references |
| Mozilla | Thunderbird | see references |
Weakness: CWE-416 · Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:L/I:L/A:N
References
- https://bugzilla.mozilla.org/show_bug.cgi?id=2059965
- https://www.mozilla.org/security/advisories/mfsa2026-82/
- https://www.mozilla.org/security/advisories/mfsa2026-84/
- https://www.mozilla.org/security/advisories/mfsa2026-85/
- https://www.mozilla.org/security/advisories/mfsa2026-86/
- https://www.mozilla.org/security/advisories/mfsa2026-87/
- https://www.mozilla.org/security/advisories/mfsa2026-88/