CVE-2026-74964
Integer overflow in Firefox/Thunderbird graphics enabling remote code execution.
Is CVE-2026-74964 being exploited?
Not confirmed. CVE-2026-74964 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 0.47% probability of exploitation in the next 30 days.
How severe is CVE-2026-74964?
CVE-2026-74964 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-2026-74964?
Yes. A fix has been recorded for CVE-2026-74964. The vendor advisory is the authority on the exact fixed version — apply it from there rather than from a summary.
What does CVE-2026-74964 affect?
CVE-2026-74964 affects Mozilla Firefox versions before 154, Firefox ESR versions before 153.1 / 140.14, Mozilla Thunderbird versions before 154 / 153.1 / 140.14. Confirm the exact affected versions against the vendor advisory before deciding you are exposed.
What should I do about CVE-2026-74964?
Update Firefox/Thunderbird to fixed versions (154 / ESR 153.1 / 140.14) immediately.
Exploitation status reflects CISA's KEV catalog as we last synced it. Check the catalog directly.
Remote code execution via crafted graphics content in browser/email client; attacker can execute arbitrary code and fully compromise user systems.
Immediate action required