Vulnerability · Published May 19, 2026 · Assigned by mozilla
CVE-2026-8974Memory safety bugs fixed in Thunderbird 140.11 and Thunderbird 151
High 8.8
In plain English
A high-severity memory corruption 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 0.4% (higher than 30% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.
Official description
Memory safety bugs present in Thunderbird 140.10 and Thunderbird 150. 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 151, Firefox ESR 140.11, Thunderbird 151, and Thunderbird 140.11.
Affected packages & fixed versions
| Ecosystem | Package | Fixed in | Advisory |
|---|---|---|---|
| AlmaLinux:10 | firefox | 140.11.0-1.el10_2 | ALSA-2026:21380 |
| AlmaLinux:8 | firefox | 140.11.0-1.el8_10.alma.1 | ALSA-2026:21382 |
| AlmaLinux:9 | firefox | 140.11.0-1.el9_8.alma.1 | ALSA-2026:21378 |
| AlmaLinux:9 | firefox-x11 | 140.11.0-1.el9_8.alma.1 | ALSA-2026:21378 |
| AlmaLinux:10 | thunderbird | 140.11.0-1.el10_2.alma.1 | ALSA-2026:22325 |
| AlmaLinux:8 | thunderbird | 140.11.0-1.el8_10.alma.1 | ALSA-2026:22643 |
| AlmaLinux:9 | thunderbird | 140.11.0-1.el9_8.alma.1 | ALSA-2026:21381 |
| Debian:12 | firefox-esr | 140.11.0esr-1~deb12u1 | DEBIAN-CVE-2026-8974 |
| Debian:13 | firefox-esr | 140.11.0esr-1~deb13u1 | DEBIAN-CVE-2026-8974 |
| Debian:14 | firefox-esr | 140.11.0esr-1 | DEBIAN-CVE-2026-8974 |
| Debian:12 | thunderbird | 1:140.11.0esr-1~deb12u1 | DEBIAN-CVE-2026-8974 |
| Debian:13 | thunderbird | 1:140.11.0esr-1~deb13u1 | DEBIAN-CVE-2026-8974 |
| Debian:14 | thunderbird | 1:140.11.0esr-1 | DEBIAN-CVE-2026-8974 |
| Rocky Linux:10 | firefox | 0:140.11.0-1.el10_2 | RLSA-2026:21380 |
| Rocky Linux:8 | firefox | 0:140.11.0-1.el8_10 | RLSA-2026:21382 |
| Rocky Linux:9 | firefox | 0:140.11.0-1.el9_8 | RLSA-2026:21378 |
| Rocky Linux:10 | thunderbird | 0:140.11.0-1.el10_2 | RLSA-2026:22325 |
| Rocky Linux:8 | thunderbird | 0:140.11.0-1.el8_10 | RLSA-2026:22643 |
| Rocky Linux:9 | thunderbird | 0:140.11.0-1.el9_8 | RLSA-2026:21381 |
| Ubuntu:22.04:LTS | mozjs102 | no fix listed | UBUNTU-CVE-2026-8974 |
| Ubuntu:24.04:LTS | mozjs102 | no fix listed | UBUNTU-CVE-2026-8974 |
| Ubuntu:24.04:LTS | mozjs115 | no fix listed | UBUNTU-CVE-2026-8974 |
| Ubuntu:22.04:LTS | mozjs78 | no fix listed | UBUNTU-CVE-2026-8974 |
| Ubuntu:22.04:LTS | mozjs91 | no fix listed | UBUNTU-CVE-2026-8974 |
| Ubuntu:22.04:LTS | thunderbird | no fix listed | UBUNTU-CVE-2026-8974 |
Affected products (as reported)
| Vendor | Product | Versions |
|---|---|---|
| Mozilla | Firefox | see references |
| Mozilla | Thunderbird | see references |
Weakness: CWE-119 · Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H