Quick answers
- Is CVE-2026-40398 exploited in the wild?
- No. Junglewise Threat Intelligence has no report of CVE-2026-40398 being exploited in the wild.
- How severe is CVE-2026-40398?
- High severity, with a CVSS score of 7.8, published 12 May 2026.
- Which products and versions are affected?
- Microsoft Windows Remote Desktop.
- Is there a fix for CVE-2026-40398?
- 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-2026-40398 attacked?
- It is attacked with local access, in an operating system.
- Am I affected by CVE-2026-40398?
- Check whether you run Microsoft Windows Remote Desktop. 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 heap-based buffer overflow (CWE-122) exists within the Windows Remote Desktop component. The vulnerability is triggered when the application improperly handles data in memory, leading to memory corruption. An attacker with low-privileged local access can exploit this flaw without any user interaction to execute code with elevated system privileges. This allows for a complete compromise of confidentiality, integrity, and availability on the local host. Microsoft has released security updates to address this issue via the MSRC update guide.
Affected products
- Microsoft Windows Remote Desktop
Timeline
- 2026-05-12: disclosed
- 2026-05-12: advisory