Remote code execution in Microsoft Excel — a widely used enterprise application; exploit could enable broad compromise if weaponized.
CVE-2026-65807
Type-confusion RCE in Microsoft Excel allowing remote arbitrary code execution.
Is CVE-2026-65807 being exploited?
Not confirmed. CVE-2026-65807 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 0.44% probability of exploitation in the next 30 days.
How severe is CVE-2026-65807?
CVE-2026-65807 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-2026-65807?
Yes. A fix has been recorded for CVE-2026-65807. The vendor advisory is the authority on the exact fixed version — apply it from there rather than from a summary.
What does CVE-2026-65807 affect?
CVE-2026-65807 affects Microsoft Excel (Office). Confirm the exact affected versions against the vendor advisory before deciding you are exposed.
What should I do about CVE-2026-65807?
Apply vendor patch/workaround ASAP; block untrusted spreadsheets and enable EDR/ATP.
Exploitation status reflects CISA's KEV catalog as we last synced it. Check the catalog directly.
Remote code execution via crafted Excel file (type confusion). Attacker can run arbitrary code, install malware, exfiltrate or modify data with user privileges.
Immediate action required
- affected>= 16.0.1 and < https://aka.ms/OfficeSecurityReleases
- affected>= 16.0.0.0 and < 16.0.5565.1001
- affected>= 19.0.0 and < https://aka.ms/OfficeSecurityReleases
- affected>= 1.0.0 and < 16.112.26081010
- affected>= 16.0.1 and < https://aka.ms/OfficeSecurityReleases
- affected>= 16.0.0 and < https://aka.ms/OfficeSecurityReleases
- affected>= 16.0.1 and < 16.112.26081010
- affected>= 16.0.0 and < 16.112.26081010
- affected>= 16.0.0.0 and < 16.0.10417.20175
As published in the CVE Program record. A version outside these ranges is not a statement that it is unaffected — vendors sometimes understate a range, and distribution-backported builds carry upstream numbers that do not reflect what was patched into them.