Remote code execution in Microsoft Outlook, a widely deployed enterprise application; could enable large-scale malware/compromise across organizations.
CVE-2026-70329
Integer overflow in Microsoft Outlook enabling remote code execution.
Is CVE-2026-70329 being exploited?
Not confirmed. CVE-2026-70329 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 0.67% probability of exploitation in the next 30 days.
How severe is CVE-2026-70329?
CVE-2026-70329 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-2026-70329?
Yes. A fix has been recorded for CVE-2026-70329. The vendor advisory is the authority on the exact fixed version — apply it from there rather than from a summary.
What does CVE-2026-70329 affect?
CVE-2026-70329 affects Microsoft Outlook, Microsoft Office (Outlook component), Windows clients. Confirm the exact affected versions against the vendor advisory before deciding you are exposed.
What should I do about CVE-2026-70329?
Apply vendor patch when released; block/scan suspicious attachments; enforce macro and email protections.
Exploitation status reflects CISA's KEV catalog as we last synced it. Check the catalog directly.
Remote code execution via integer overflow in Outlook; attackers can run arbitrary code, install malware, or fully compromise user systems over the network.
Immediate action required
- affected>= 16.0.1 and < https://aka.ms/OfficeSecurityReleases
- affected>= 19.0.0 and < https://aka.ms/OfficeSecurityReleases
- affected>= 16.0.1 and < https://aka.ms/OfficeSecurityReleases
- affected>= 16.0.0 and < https://aka.ms/OfficeSecurityReleases
- affected>= 16.0.0.0 and < 16.0.5565.1000
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.