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PatchSiren cyber security CVE debrief

CVE-2026-42915 Microsoft CVE debrief

CVE-2026-42915 is a vulnerability in Windows TCP/IP that allows an authorized attacker to deny service over an adjacent network. The vulnerability has a CVSS score of 5.7 and a severity of MEDIUM. It was published on 2026-06-09T17:17:11.780Z and modified on 2026-06-11T19:52:04.170Z.

Vendor
Microsoft
Product
Windows 10 Version 21H2
CVSS
MEDIUM 5.5
CISA KEV
Not listed in stored evidence
Original CVE published
2026-06-09
Original CVE updated
2026-06-19
Advisory published
2026-06-09
Advisory updated
2026-06-19

Who should care

Administrators of Windows systems, particularly those with adjacent networks, should be aware of this vulnerability and take necessary precautions.

Technical summary

The vulnerability is caused by an incorrect calculation of buffer size in Windows TCP/IP. This allows an authorized attacker to deny service over an adjacent network.

Defensive priority

MEDIUM

Recommended defensive actions

  • Apply patches or updates from the vendor as soon as possible.
  • Restrict access to affected systems and networks.
  • Monitor network activity for suspicious behavior.

Evidence notes

The vulnerability is described in the CVE record [cve-org]. Detailed information can be found in the NVD detail [nvd].

Sources and references

Verified primary and authoritative sources

  • CVE-2026-42915 CVE Program record

    Publisher, destination, and source semantics verified

    URL: https://www.cve.org/CVERecord?id=CVE-2026-42915

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

  • CVE-2026-42915 NVD vulnerability detail

    Publisher, destination, and source semantics verified

    URL: https://nvd.nist.gov/vuln/detail/CVE-2026-42915

    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.