Is CVE-2026-40418 exploited in the wild?

No. Junglewise Threat Intelligence has no report of CVE-2026-40418 being exploited in the wild.

How severe is CVE-2026-40418?

High severity, with a CVSS score of 7.8, published 12 May 2026.

Is there a fix for CVE-2026-40418?

No fixed version is recorded yet. Check the vendor's advisory in the references below. If you run it, Junglewise drafts a mitigation that fits your setup and applies it once you approve, with senior security engineers behind it.

How is CVE-2026-40418 attacked?

It is attacked with local access, in a network appliance.

Am I affected by CVE-2026-40418?

Check whether you run Microsoft Office Click-to-Run. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

CVE-2026-40418: Microsoft Office Click-to-Run use after free privilege escalation

CVE-2026-40418 · Severity: high · CVSS 7.8 · Published 2026-05-12

A security vulnerability exists in the Microsoft Office Click-to-Run service, which is responsible for installing and updating Office applications. An attacker who already has basic access to a computer could exploit this flaw to gain full administrative control over the system. This could allow them to bypass security restrictions, access sensitive data, or install malicious software across the organization.

Technologies: Microsoft Office Click-to-Run. Vendors: Microsoft.

Quick answers

Is CVE-2026-40418 exploited in the wild?: No. Junglewise Threat Intelligence has no report of CVE-2026-40418 being exploited in the wild.
How severe is CVE-2026-40418?: High severity, with a CVSS score of 7.8, published 12 May 2026.
Which products and versions are affected?: Microsoft Office Click-to-Run.
Is there a fix for CVE-2026-40418?: No fixed version is recorded yet. Check the vendor's advisory in the references below. If you run it, Junglewise drafts a mitigation that fits your setup and applies it once you approve, with senior security engineers behind it.
How is CVE-2026-40418 attacked?: It is attacked with local access, in a network appliance.
Am I affected by CVE-2026-40418?: Check whether you run Microsoft Office Click-to-Run. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

Technical details

A use-after-free vulnerability (CWE-416) exists within the Microsoft Office Click-to-Run component. The flaw is triggered when the application continues to use a pointer after the memory it references has been freed, leading to memory corruption. An attacker with local access and low-level privileges can exploit this condition to execute arbitrary code with elevated system permissions. The attack requires no user interaction and has a low complexity, making it a reliable method for privilege escalation once initial access to a host is established. Microsoft has released security updates to address this issue.

Affected products

Microsoft Office Click-to-Run

Timeline

2026-05-12: disclosed
2026-05-12: advisory

References

https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-40418

This page as Markdown. Free to reuse under CC BY 4.0 with a link back.