CVE-2026-7321 is a critical vulnerability in Mozilla Firefox's WebRTC Networking component where incorrect boundary conditions allow sandbox escape. This memory safety issue could enable an attacker to break out of the sandbox environment, potentially leading to arbitrary code execution with high impact on confidentiality, integrity, and availability. The vulnerability was fixed in Firefox 150, Thunderbird 150, Firefox ESR 140.10.1, and Thunderbird 140.10.1. The Mozilla Foundation security advisories MFSA2026-30 and MFSA2026-33 provide detailed information on this and other related vulnerabilities fixed in these releases.

The vulnerability allows sandbox escape, which can lead to full compromise of the affected application environment. The CVSS score of 9.6 reflects critical impact on confidentiality, integrity, and availability. Exploitation could result in arbitrary code execution outside the sandbox restrictions. However, no known exploits in the wild have been reported as of the advisory date.

Mozilla has released official fixes for this vulnerability in Firefox 150, Thunderbird 150, Firefox ESR 140.10.1, and Thunderbird 140.10.1. Users and administrators should apply these updates promptly to remediate the issue. Since this is not a cloud service, remediation depends on user-side patching. There are no vendor advisories indicating that no action is required or that the issue is already mitigated without patching.