PatchSiren

PatchSiren cyber security CVE debrief

CVE-2026-42993 Microsoft CVE debrief

CVE-2026-42993 is a high-severity vulnerability in the Remote Desktop Client that allows an unauthorized attacker to execute code over a network. The vulnerability is caused by a heap-based buffer overflow and has a CVSS score of 7.5.

Vendor
Microsoft
Product
Windows 10 Version 21H2
CVSS
HIGH 7.5
CISA KEV
Not listed in stored evidence
Original CVE published
2026-06-09
Original CVE updated
2026-06-15
Advisory published
2026-06-09
Advisory updated
2026-06-15

Who should care

Administrators and users of Microsoft Remote Desktop Client are advised to take action to mitigate this vulnerability.

Technical summary

The vulnerability is a heap-based buffer overflow in the Remote Desktop Client, which allows an unauthorized attacker to execute code over a network. The CVSS vector for this vulnerability is CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:H.

Defensive priority

High

Recommended defensive actions

  • Apply patches or updates provided by Microsoft to vulnerable systems.
  • Implement network segmentation and isolation to limit the attack surface.
  • Monitor Remote Desktop Client usage and detect potential exploitation attempts.

Evidence notes

The vulnerability is described in the CVE record and NVD detail pages. Microsoft has provided a vendor advisory for this vulnerability.

Sources and references

Verified primary and authoritative sources

  • CVE-2026-42993 CVE Program record

    Publisher, destination, and source semantics verified

    URL: https://www.cve.org/CVERecord?id=CVE-2026-42993

    CVE Program - Official CVE Program record with source-provided CVE metadata.

  • CVE-2026-42993 NVD vulnerability detail

    Publisher, destination, and source semantics verified

    URL: https://nvd.nist.gov/vuln/detail/CVE-2026-42993

    NIST National Vulnerability Database - Official NIST NVD detail page and source-specific vulnerability assessment.

Supplemental references

Methodology and review provenance

AI-assisted synthesis based on stored public vulnerability evidence. System validation, approval state, and publication status do not by themselves establish human review of this revision. PatchSiren helps prioritize defensive review and does not prove exposure or remediation on any system.