Browser sandbox escape in Mozilla Firefox (widely deployed). Remote code execution in a common enterprise client merits org-wide attention.
CVE-2026-100786
Use-after-free sandbox escape in Firefox Graphics enabling remote code execution.
Is CVE-2026-100786 being exploited?
Not confirmed. CVE-2026-100786 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-2026-100786?
CVE-2026-100786 is rated Critical with a CVSS score of 9.6. 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-2026-100786?
Yes. A fix has been recorded for CVE-2026-100786. The vendor advisory is the authority on the exact fixed version — apply it from there rather than from a summary.
What does CVE-2026-100786 affect?
CVE-2026-100786 affects Mozilla Firefox (desktop) versions prior to 157, Firefox ESR versions prior to 153.4, 140.17, 115.42. Confirm the exact affected versions against the vendor advisory before deciding you are exposed.
What should I do about CVE-2026-100786?
Update all Firefox installations to the listed fixed versions immediately.
Exploitation status reflects CISA's KEV catalog as we last synced it. Check the catalog directly.
Remote sandbox escape via crafted web content allowing arbitrary code execution on affected Firefox clients.
Immediate action required