Vulnerability · Published Apr 21, 2026 · Assigned by mozilla
CVE-2026-6759Use-after-free in the Widget: Cocoa component
High 7.5
In plain English
A high-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 0.4% (higher than 30% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.
Severity (CVSS 3.1)7.5High
Exploit odds (30 days)0.4%top 69.7% of all CVEs
Exploited in the wildNo reportsCISA SSVC: none
Attack toolingNoneno public tooling known
Official description
Use-after-free in the Widget: Cocoa component. This vulnerability was fixed in Firefox 150, Firefox ESR 140.10, Thunderbird 150, and Thunderbird 140.10.
Affected packages & fixed versions
| Ecosystem | Package | Fixed in | Advisory |
|---|---|---|---|
| AlmaLinux:10 | firefox | 140.10.0-1.el10_1 | ALSA-2026:10767 |
| AlmaLinux:8 | firefox | 140.10.0-1.el8_10.alma.1 | ALSA-2026:10766 |
| AlmaLinux:9 | firefox | 140.10.0-1.el9_7.alma.1 | ALSA-2026:10757 |
| AlmaLinux:9 | firefox-x11 | 140.10.0-1.el9_7.alma.1 | ALSA-2026:10757 |
| AlmaLinux:10 | thunderbird | 140.10.0-1.el10_1.alma.1 | ALSA-2026:12285 |
| AlmaLinux:8 | thunderbird | 140.10.0-1.el8_10.alma.1 | ALSA-2026:13537 |
| AlmaLinux:9 | thunderbird | 140.10.0-1.el9_7.alma.1 | ALSA-2026:15892 |
| AlmaLinux:9 | thunderbird | 140.10.1-1.el9_8.alma.1 | ALSA-2026:19348 |
| Rocky Linux:10 | firefox | 0:140.10.0-1.el10_1 | RLSA-2026:10767 |
| Rocky Linux:8 | firefox | 0:140.10.0-1.el8_10 | RLSA-2026:10766 |
| Rocky Linux:9 | firefox | 0:140.10.0-1.el9_7 | RLSA-2026:10757 |
| Rocky Linux:9 | firefox | 0:140.10.0-1.el9_7 | RLSA-2026:19201 |
| Rocky Linux:10 | thunderbird | 0:140.10.0-1.el10_1 | RLSA-2026:12285 |
| Rocky Linux:8 | thunderbird | 0:140.10.0-1.el8_10 | RLSA-2026:13537 |
| Rocky Linux:9 | thunderbird | 0:140.10.1-1.el9_8 | RLSA-2026:19348 |
| Rocky Linux:9 | thunderbird | 0:140.10.0-1.el9_7 | RLSA-2026:15892 |
| Ubuntu:22.04:LTS | mozjs102 | no fix listed | UBUNTU-CVE-2026-6759 |
| Ubuntu:24.04:LTS | mozjs102 | no fix listed | UBUNTU-CVE-2026-6759 |
| Ubuntu:24.04:LTS | mozjs115 | no fix listed | UBUNTU-CVE-2026-6759 |
| Ubuntu:22.04:LTS | mozjs78 | no fix listed | UBUNTU-CVE-2026-6759 |
| Ubuntu:22.04:LTS | mozjs91 | no fix listed | UBUNTU-CVE-2026-6759 |
| Ubuntu:22.04:LTS | thunderbird | no fix listed | UBUNTU-CVE-2026-6759 |
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:N/S:U/C:N/I:N/A:H