High-severity privilege escalation in widely used Mozilla Firefox and Thunderbird clients; impacts many endpoints and merits org-wide distribution.
CVE-2026-92009
Firefox/Thunderbird local privilege escalation via Canvas WebGL boundary bug
Is CVE-2026-92009 being exploited?
Not confirmed. CVE-2026-92009 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.
How severe is CVE-2026-92009?
CVE-2026-92009 is rated High with a CVSS score of 8.8. 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-2026-92009?
Yes. A fix has been recorded for CVE-2026-92009. The vendor advisory is the authority on the exact fixed version — apply it from there rather than from a summary.
What does CVE-2026-92009 affect?
CVE-2026-92009 affects Firefox < 156, Firefox ESR < 115.41, Firefox ESR < 140.16, Firefox ESR < 153.3, and 3 further products or versions. Confirm the exact affected versions against the vendor advisory before deciding you are exposed.
What should I do about CVE-2026-92009?
Update to the listed fixed Firefox/Thunderbird versions immediately
Exploitation status reflects CISA's KEV catalog as we last synced it. Check the catalog directly.
Local privilege escalation allowing sandbox escape or higher-privilege code execution via malformed WebGL/Canvas data.
Patch when possible