Vulnerability · Published Apr 28, 2026 · Assigned by mozilla
CVE-2026-7321Sandbox escape due to incorrect boundary conditions in the WebRTC: Networking component
Critical 9.6
In plain English
A critical-severity buffer overflow 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 0.3% (higher than 18% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.
Severity (CVSS 3.1)9.6Critical
Exploit odds (30 days)0.3%top 82.4% of all CVEs
Exploited in the wildNo reportsCISA SSVC: none
Attack toolingNoneno public tooling known
Official description
Sandbox escape due to incorrect boundary conditions in the WebRTC: Networking component. This vulnerability was fixed in Firefox 150, Thunderbird 150, Firefox ESR 140.10.1, and Thunderbird 140.10.1.
Affected packages & fixed versions
| Ecosystem | Package | Fixed in | Advisory |
|---|---|---|---|
| AlmaLinux:10 | firefox | 140.10.1-1.el10_2 | ALSA-2026:19157 |
| AlmaLinux:8 | firefox | 140.10.1-1.el8_10.alma.1 | ALSA-2026:19588 |
| AlmaLinux:9 | firefox | 140.10.1-1.el9_8.alma.1 | ALSA-2026:19370 |
| AlmaLinux:9 | firefox-x11 | 140.10.1-1.el9_8.alma.1 | ALSA-2026:19370 |
| AlmaLinux:10 | thunderbird | 140.10.1-1.el10_2.alma.1 | ALSA-2026:19153 |
| AlmaLinux:8 | thunderbird | 140.10.1-1.el8_10.alma.1 | ALSA-2026:20586 |
| AlmaLinux:9 | thunderbird | 140.10.1-1.el9_8.alma.1 | ALSA-2026:19348 |
| Debian:12 | firefox-esr | 140.10.1esr-1~deb12u1 | DEBIAN-CVE-2026-7321 |
| Debian:13 | firefox-esr | 140.10.1esr-1~deb13u1 | DEBIAN-CVE-2026-7321 |
| Debian:14 | firefox-esr | 140.10.1esr-1 | DEBIAN-CVE-2026-7321 |
| Debian:12 | thunderbird | 1:140.10.1esr-1~deb12u1 | DEBIAN-CVE-2026-7321 |
| Debian:13 | thunderbird | 1:140.10.1esr-1~deb13u1 | DEBIAN-CVE-2026-7321 |
| Debian:14 | thunderbird | 1:140.10.1esr-1 | DEBIAN-CVE-2026-7321 |
| Rocky Linux:8 | firefox | 0:140.10.1-1.el8_10 | RLSA-2026:19588 |
| Rocky Linux:9 | firefox | 0:140.10.1-1.el9_8 | RLSA-2026:19370 |
| Rocky Linux:10 | thunderbird | 0:140.10.1-1.el10_2 | RLSA-2026:19153 |
| Rocky Linux:8 | thunderbird | 0:140.10.1-1.el8_10 | RLSA-2026:20586 |
| Rocky Linux:9 | thunderbird | 0:140.10.1-1.el9_8 | RLSA-2026:19348 |
Affected products (as reported)
| Vendor | Product | Versions |
|---|---|---|
| Mozilla | Firefox | see references |
| Mozilla | Thunderbird | see references |
Weakness: CWE-120 · Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:H/A:H