High-severity remote code execution in widely used Mozilla products (Firefox/Thunderbird) via WebGPU memory corruption; broad impact and urgent patching required.
CVE-2026-16393
WebGPU boundary bug in Firefox/Thunderbird allows remote code execution
Is CVE-2026-16393 being exploited?
Not confirmed. CVE-2026-16393 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-2026-16393?
CVE-2026-16393 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-2026-16393?
Yes. A fix has been recorded for CVE-2026-16393. The vendor advisory is the authority on the exact fixed version — apply it from there rather than from a summary.
What does CVE-2026-16393 affect?
CVE-2026-16393 affects Mozilla Firefox < 153, Mozilla Thunderbird < 153, Gecko-based apps using WebGPU. Confirm the exact affected versions against the vendor advisory before deciding you are exposed.
What should I do about CVE-2026-16393?
Update Firefox and Thunderbird to 153+ immediately
Exploitation status reflects CISA's KEV catalog as we last synced it. Check the catalog directly.
Memory-corruption in WebGPU can be triggered by crafted web content, enabling remote arbitrary code execution or sandbox escape.
Immediate action required