Remote-code-exec JIT bug in widely used Mozilla products (Firefox/Thunderbird) with CVSS 9.8; broad client impact and high exploit potential warrants wide distribution.
CVE-2026-16410
JIT miscompilation in Firefox/Thunderbird enabling remote code execution
Is CVE-2026-16410 being exploited?
Not confirmed. CVE-2026-16410 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 0.30% probability of exploitation in the next 30 days.
How severe is CVE-2026-16410?
CVE-2026-16410 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-2026-16410?
Yes. A fix has been recorded for CVE-2026-16410. The vendor advisory is the authority on the exact fixed version — apply it from there rather than from a summary.
What does CVE-2026-16410 affect?
CVE-2026-16410 affects Mozilla Firefox <153, Mozilla Thunderbird <153, Products embedding SpiderMonkey JS engine. Confirm the exact affected versions against the vendor advisory before deciding you are exposed.
What should I do about CVE-2026-16410?
Update Firefox and Thunderbird to 153 or later immediately
Exploitation status reflects CISA's KEV catalog as we last synced it. Check the catalog directly.
Remote code execution via crafted JavaScript causing memory corruption and arbitrary code execution in the browser process.
Immediate action required