CVE-2026-6747 Mozilla CVE debrief

Who should care

Organizations and individuals using Firefox, Thunderbird, or Firefox ESR should prioritize patching this vulnerability. The vulnerability's high severity and potential for code execution make it a critical concern for defenders.

Technical summary

The CVE-2026-6747 vulnerability is a use-after-free issue in the WebRTC component. This type of vulnerability occurs when a program attempts to access memory after it has been freed, potentially leading to a crash or code execution. The vulnerability was addressed in Firefox 150, Firefox ESR 140.10, Thunderbird 150, and Thunderbird 140.10. The CVSS vector for this vulnerability is CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H, indicating a high severity.

Defensive priority

Defenders should prioritize patching CVE-2026-6747 due to its high severity and potential for code execution. Immediate action is necessary to prevent potential exploitation.

Recommended defensive actions

• Apply patches for Firefox 150, Firefox ESR 140.10, Thunderbird 150, and Thunderbird 140.10.
• Ensure all users and systems are updated with the latest versions.
• Monitor for any suspicious activity related to WebRTC components.
• Implement compensating controls, such as enhanced monitoring and incident response planning.
• Review and update incident response plans to address potential exploitation.

Evidence notes

The CVE-2026-6747 vulnerability was publicly disclosed on 2026-04-21 and last modified on 2026-06-30. The vulnerability has a CVSS score of 7.5 and a severity of HIGH. The CVE is associated with CWE-416 and CWE-825.

Sources and references

Methodology and review provenance

AI-assisted synthesis based on stored public vulnerability evidence. System validation, approval state, and publication status do not by themselves establish human review of this revision. PatchSiren helps prioritize defensive review and does not prove exposure or remediation on any system.