PatchSiren cyber security CVE debrief
CVE-2026-16379 Mozilla CVE debrief
CVE-2026-16379 is a critical vulnerability in the DOM: Content Processes component of Firefox, Firefox ESR, Thunderbird, and Thunderbird 140.13. The vulnerability allows for privilege escalation and was fixed in Firefox 153, Firefox ESR 140.13, Thunderbird 153, and Thunderbird 140.13. The CVSS score for this vulnerability is 9.8, indicating a high severity level. Users of these products should update to the latest versions to mitigate the vulnerability. The vulnerability's impact is likely significant due to its critical severity and the wide range of affected products.
- Vendor
- Mozilla
- Product
- Firefox
- CVSS
- CRITICAL 9.8
- CISA KEV
- Not listed in stored evidence
- Original CVE published
- 2026-07-21
- Original CVE updated
- 2026-07-22
- Advisory published
- 2026-07-21
- Advisory updated
- 2026-07-22
Who should care
This vulnerability affects users of Firefox, Firefox ESR, Thunderbird, and Thunderbird 140.13. Users of these products should update to the latest versions to mitigate the vulnerability. Additionally, security teams and vulnerability management teams should review the official advisories and assess their exposure to this vulnerability.
Technical summary
The vulnerability is a privilege escalation issue in the DOM: Content Processes component. It was fixed in Firefox 153, Firefox ESR 140.13, Thunderbird 153, and Thunderbird 140.13. The CVSS vector for this vulnerability is CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H. This vulnerability affects users of Firefox, Firefox ESR, Thunderbird, and Thunderbird 140.13, and users should update to the latest versions to mitigate the vulnerability.
Defensive priority
High
Recommended defensive actions
- Update Firefox to version 153 or later
- Update Firefox ESR to version 140.13 or later
- Update Thunderbird to version 153 or later
- Update Thunderbird to version 140.13 or later
- Review compensating controls for exposed systems while remediation is scheduled and verified
- Check relevant monitoring, detection, and logs for exposed assets that need extra review
- Track exceptions, retest remediated assets, and close the item only after evidence is documented
Evidence notes
The vulnerability was reported by [email protected]. The CVE record was published on 2026-07-21T13:17:13.067Z and modified on 2026-07-22T20:16:55.057Z. Evidence is limited to public sources and may not reflect the full scope or impact of the vulnerability. Defenders should verify affected systems and review official advisories for specific guidance.
Official resources
AI-assisted PatchSiren debrief based on the supplied source corpus. The CVE record was published on 2026-07-21T13:17:13.067Z and has not been modified since then.