CVE-2026-74946
Privilege escalation via WebGL Canvas boundary bug in Firefox/Thunderbird.
Is CVE-2026-74946 being exploited?
Not confirmed. CVE-2026-74946 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 0.33% probability of exploitation in the next 30 days.
How severe is CVE-2026-74946?
CVE-2026-74946 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-2026-74946?
Yes. A fix has been recorded for CVE-2026-74946. The vendor advisory is the authority on the exact fixed version — apply it from there rather than from a summary.
What does CVE-2026-74946 affect?
CVE-2026-74946 affects Mozilla Firefox (prior to 154), Firefox ESR (prior to 115.39, 140.14, 153.1), Mozilla Thunderbird (prior to 154). Confirm the exact affected versions against the vendor advisory before deciding you are exposed.
What should I do about CVE-2026-74946?
Update to Firefox 154 / ESR 115.39,140.14,153.1 and Thunderbird 154 immediately.
Exploitation status reflects CISA's KEV catalog as we last synced it. Check the catalog directly.
Sandbox escape and local privilege escalation via crafted WebGL/Canvas content, enabling code execution in the browser/host context.
Patch when possible