CVE-2026-16370
DOM networking mitigation bypass in Firefox/Thunderbird allowing web-based exploitation.
Is CVE-2026-16370 being exploited?
Not confirmed. CVE-2026-16370 does not appear in CISA's Known Exploited Vulnerabilities catalog, which records only exploitation that has been observed and reported publicly. That is evidence of absence of a report, not evidence the flaw is unattacked. EPSS currently estimates a 0.31% probability of exploitation in the next 30 days.
How severe is CVE-2026-16370?
CVE-2026-16370 is rated Critical with a CVSS score of 9.1. Severity describes how bad exploitation would be, not how likely it is: pair it with exploitation evidence before deciding what to patch first.
Is there a patch for CVE-2026-16370?
Yes. A fix has been recorded for CVE-2026-16370. The vendor advisory is the authority on the exact fixed version — apply it from there rather than from a summary.
What does CVE-2026-16370 affect?
CVE-2026-16370 affects Mozilla Firefox < 153, Mozilla Thunderbird < 153. Confirm the exact affected versions against the vendor advisory before deciding you are exposed.
What should I do about CVE-2026-16370?
Update Firefox and Thunderbird to version 153+ immediately
Exploitation status reflects CISA's KEV catalog as we last synced it. Check the catalog directly.
Attackers can bypass DOM networking protections via crafted web content, enabling cross-origin network abuse, data exfiltration or possible remote code execution.
Immediate action required