CVE-2026-74949
Use-after-free in Firefox Canvas2D enabling local privilege escalation.
Is CVE-2026-74949 being exploited?
Not confirmed. CVE-2026-74949 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 0.31% probability of exploitation in the next 30 days.
How severe is CVE-2026-74949?
CVE-2026-74949 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-2026-74949?
Yes. A fix has been recorded for CVE-2026-74949. The vendor advisory is the authority on the exact fixed version — apply it from there rather than from a summary.
What does CVE-2026-74949 affect?
CVE-2026-74949 affects Mozilla Firefox (pre-154), Firefox ESR (pre-140.14 / pre-153.1), Mozilla Thunderbird (pre-154), Thunderbird ESR (pre-140.14 / pre-153.1). Confirm the exact affected versions against the vendor advisory before deciding you are exposed.
What should I do about CVE-2026-74949?
Update Firefox/Thunderbird to 154 or ESR 140.14/153.1+ immediately
Exploitation status reflects CISA's KEV catalog as we last synced it. Check the catalog directly.
Canvas2D use-after-free can be exploited to escalate privileges, potentially escape the browser sandbox and run code with higher rights.
Patch when possible