Is CVE-2026-54990 exploited in the wild?

No. Junglewise Threat Intelligence has no report of CVE-2026-54990 being exploited in the wild.

How severe is CVE-2026-54990?

Critical severity, with a CVSS score of 9.8, published 14 July 2026.

Which products and versions are affected?

Microsoft Windows 11 10.0.26100.0 to 10.0.26100.8875; Microsoft Windows Server 2025 10.0.26100.0 to 10.0.26100.33158.

Is there a fix for CVE-2026-54990?

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-2026-54990 attacked?

It is attacked over the network, in an operating system.

Am I affected by CVE-2026-54990?

Check whether you run Microsoft Windows 11 or Microsoft Windows Server 2025 at an affected version. 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-2026-54990: Microsoft Remote Desktop Client heap overflow remote code execution

CVE-2026-54990 · Severity: critical · CVSS 9.8 · Published 2026-07-14

A critical vulnerability has been identified in the Microsoft Remote Desktop Client, a tool used to connect to and control remote computers. An unauthorized attacker could exploit this flaw over a network to execute malicious code on a target system without any user interaction. This could lead to a complete takeover of the affected machine, potentially resulting in data theft, service disruption, or further lateral movement within a corporate network.

Technologies: Microsoft Windows 11, Microsoft Windows Server 2025. Vendors: Microsoft.

Quick answers

Is CVE-2026-54990 exploited in the wild?: No. Junglewise Threat Intelligence has no report of CVE-2026-54990 being exploited in the wild.
How severe is CVE-2026-54990?: Critical severity, with a CVSS score of 9.8, published 14 July 2026.
Which products and versions are affected?: Microsoft Windows 11 10.0.26100.0 to 10.0.26100.8875; Microsoft Windows Server 2025 10.0.26100.0 to 10.0.26100.33158.
Is there a fix for CVE-2026-54990?: 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-2026-54990 attacked?: It is attacked over the network, in an operating system.
Am I affected by CVE-2026-54990?: Check whether you run Microsoft Windows 11 or Microsoft Windows Server 2025 at an affected version. 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 vulnerability (CWE-122) exists in the Microsoft Remote Desktop Client. The flaw is triggered when the client processes specially crafted network packets, allowing an unauthenticated attacker to achieve remote code execution (RCE) with the privileges of the user running the client. The attack vector is network-based and requires no prior authentication or user interaction (UI:N). Affected versions include various builds of Windows 11 and Windows Server 2025; users are advised to apply the latest security updates from Microsoft to mitigate this risk.

Affected products

Microsoft Windows 11 Version 24H2 10.0.26100.0 to 10.0.26100.8875
Microsoft Windows 11 Version 25H2 10.0.26200.0 to 10.0.26200.8875
Microsoft Windows 11 version 26H1 10.0.26200.0 to 10.0.28000.2269
Microsoft Windows Server 2025 10.0.26100.0 to 10.0.26100.33158

Timeline

2026-07-14: disclosed
2026-07-14: advisory

References

https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-54990

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