Affects widely used Firefox/Thunderbird; high risk; could disrupt users across industries.
CVE-2026-4715
Canvas2D uninitialized memory may cause memory corruption in Firefox/Thunderbird before 149/140.9.
Is CVE-2026-4715 being exploited?
Not confirmed. CVE-2026-4715 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 0.43% probability of exploitation in the next 30 days.
How severe is CVE-2026-4715?
CVE-2026-4715 is rated Critical with a CVSS score of 9.1. 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-2026-4715?
Yes. A fix has been recorded for CVE-2026-4715. The vendor advisory is the authority on the exact fixed version — apply it from there rather than from a summary.
What does CVE-2026-4715 affect?
CVE-2026-4715 affects Firefox <149, Firefox ESR <140.9, Thunderbird <149, Thunderbird <140.9. Confirm the exact affected versions against the vendor advisory before deciding you are exposed.
What should I do about CVE-2026-4715?
Update when patched; monitor Mozilla advisories.
Exploitation status reflects CISA's KEV catalog as we last synced it. Check the catalog directly.
Remote code execution or crash via crafted Canvas2D content in browser/email rendering.
Patch when possible