High-severity RCE in widely-used Mozilla Firefox/Thunderbird WebAssembly component; affects many users and can enable remote compromise.
CVE-2026-16368
WebAssembly boundary bug in Firefox/Thunderbird enables remote code execution.
Is CVE-2026-16368 being exploited?
Not confirmed. CVE-2026-16368 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 0.39% probability of exploitation in the next 30 days.
How severe is CVE-2026-16368?
CVE-2026-16368 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-2026-16368?
Yes. A fix has been recorded for CVE-2026-16368. The vendor advisory is the authority on the exact fixed version — apply it from there rather than from a summary.
What does CVE-2026-16368 affect?
CVE-2026-16368 affects Mozilla Firefox < 153, Firefox ESR < 140.13, Mozilla Thunderbird < 153, Thunderbird ESR < 140.13. Confirm the exact affected versions against the vendor advisory before deciding you are exposed.
What should I do about CVE-2026-16368?
Update to Firefox/Thunderbird 153 or ESR 140.13 immediately.
Exploitation status reflects CISA's KEV catalog as we last synced it. Check the catalog directly.
Remote code execution via crafted WebAssembly causing memory corruption and possible sandbox escape in browser/email client.
Immediate action required