CVE-2026-16382
Service Worker DOM mitigation bypass in Firefox/Thunderbird enabling web-based exploits
Is CVE-2026-16382 being exploited?
Not confirmed. CVE-2026-16382 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 0.38% probability of exploitation in the next 30 days.
How severe is CVE-2026-16382?
CVE-2026-16382 is rated Critical with a CVSS score of 9.8. 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-2026-16382?
Yes. A fix has been recorded for CVE-2026-16382. The vendor advisory is the authority on the exact fixed version — apply it from there rather than from a summary.
What does CVE-2026-16382 affect?
CVE-2026-16382 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-2026-16382?
Update Firefox/Thunderbird to 153+ immediately
Exploitation status reflects CISA's KEV catalog as we last synced it. Check the catalog directly.
Bypass Service Worker/DOM mitigations allowing remote attackers to run malicious scripts, persist via service workers, and exfiltrate data.
Immediate action required