CVE-2026-42909

CVE-2026-42909 is a high-severity vulnerability in Microsoft Remote Desktop Client with a CVSS 3.x base score of 7.5. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-787.

Key facts

• Severity: High (CVSS 3.x base score 7.5)
• EPSS exploit prediction: 0% (32nd percentile)
• Actively exploited: Not listed in CISA KEV
• EU (EUVD) id: EUVD-2026-35599
• Weakness: CWE-787
• Affected product: Microsoft Remote Desktop Client
• Published: 2026-06-09
• Last modified: 2026-06-17

Description

Heap-based buffer overflow in Remote Desktop Client allows an unauthorized attacker to execute code over a network.

Frequently asked questions

What is CVE-2026-42909?

Heap-based buffer overflow in Remote Desktop Client allows an unauthorized attacker to execute code over a network.

How severe is CVE-2026-42909?

CVE-2026-42909 has a CVSS 3.x base score of 7.5, rated high severity. It is exploitable over network with high attack complexity, requires no privileges and user interaction. Impact on confidentiality is high, integrity high, and availability high.

Is CVE-2026-42909 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (32nd percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2026-42909?

CVE-2026-42909 primarily affects Microsoft Remote Desktop Client. In total, 26 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.

How do I fix CVE-2026-42909?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.

Does CVE-2026-42909 have an EU (EUVD) identifier?

Yes. CVE-2026-42909 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-35599.

When was CVE-2026-42909 published?

CVE-2026-42909 was published on 2026-06-09 and last updated on 2026-06-17.

References

• https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-42909

Affected products (26)

• cpe:2.3:a:microsoft:remote_desktop_client:*:*:*:*:*:windows:*:*
• cpe:2.3:a:microsoft:windows_app:*:*:*:*:*:windows:*:*
• cpe:2.3:o:microsoft:windows_10_1607:*:*:*:*:*:*:x64:*
• cpe:2.3:o:microsoft:windows_10_1607:*:*:*:*:*:*:x86:*
• cpe:2.3:o:microsoft:windows_10_1809:*:*:*:*:*:*:x64:*
• cpe:2.3:o:microsoft:windows_10_1809:*:*:*:*:*:*:x86:*
• cpe:2.3:o:microsoft:windows_10_21h2:*:*:*:*:*:*:arm64:*
• cpe:2.3:o:microsoft:windows_10_21h2:*:*:*:*:*:*:x64:*
• cpe:2.3:o:microsoft:windows_10_21h2:*:*:*:*:*:*:x86:*
• cpe:2.3:o:microsoft:windows_10_22h2:*:*:*:*:*:*:arm64:*
• cpe:2.3:o:microsoft:windows_10_22h2:*:*:*:*:*:*:x64:*
• cpe:2.3:o:microsoft:windows_10_22h2:*:*:*:*:*:*:x86:*
• cpe:2.3:o:microsoft:windows_11_23h2:*:*:*:*:*:*:arm64:*
• cpe:2.3:o:microsoft:windows_11_23h2:*:*:*:*:*:*:x64:*
• cpe:2.3:o:microsoft:windows_11_24h2:*:*:*:*:*:*:arm64:*
• cpe:2.3:o:microsoft:windows_11_24h2:*:*:*:*:*:*:x64:*
• cpe:2.3:o:microsoft:windows_11_25h2:*:*:*:*:*:*:arm64:*
• cpe:2.3:o:microsoft:windows_11_25h2:*:*:*:*:*:*:x64:*
• cpe:2.3:o:microsoft:windows_11_26h1:*:*:*:*:*:*:arm64:*
• cpe:2.3:o:microsoft:windows_11_26h1:*:*:*:*:*:*:x64:*
• cpe:2.3:o:microsoft:windows_server_2012:-:*:*:*:*:*:*:*
• cpe:2.3:o:microsoft:windows_server_2012:r2:*:*:*:*:*:*:*
• cpe:2.3:o:microsoft:windows_server_2016:*:*:*:*:*:*:*:*
• cpe:2.3:o:microsoft:windows_server_2019:*:*:*:*:*:*:*:*
• cpe:2.3:o:microsoft:windows_server_2022:*:*:*:*:*:*:*:*
• cpe:2.3:o:microsoft:windows_server_2025:*:*:*:*:*:*:x64:*

More vulnerabilities in Microsoft Remote Desktop Client

• CVE-2026-42985 — High (CVSS 8.8): Heap-based buffer overflow in Remote Desktop Client allows an unauthorized attacker to execute code over a network.
• CVE-2026-32157 — High (CVSS 8.8): Use after free in Remote Desktop Client allows an unauthorized attacker to execute code over a network.
• CVE-2025-58718 — High (CVSS 8.8): Use after free in Remote Desktop Client allows an unauthorized attacker to execute code over a network.
• CVE-2025-48817 — High (CVSS 8.8): Relative path traversal in Remote Desktop Client allows an unauthorized attacker to execute code over a network.
• CVE-2025-26645 — High (CVSS 8.8): Relative path traversal in Remote Desktop Client allows an unauthorized attacker to execute code over a network.
• CVE-2024-38131 — High (CVSS 8.8): Clipboard Virtual Channel Extension Remote Code Execution Vulnerability

All CVEs affecting Microsoft Remote Desktop Client →

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