CVE-2026-42915: CWE-131: Incorrect Calculation of Buffer Size in Microsoft Windows 10 Version 21H2
CVE-2026-42915 is a medium severity vulnerability in Microsoft Windows 10 Version 21H2 caused by incorrect calculation of buffer size in the Windows TCP/IP stack. This flaw allows an authorized attacker on an adjacent network to cause a denial of service condition. The vulnerability does not impact confidentiality or integrity but affects availability. An official fix is available from Microsoft.
AI Analysis
Technical Summary
This vulnerability (CVE-2026-42915) involves an incorrect calculation of buffer size in the TCP/IP implementation of Windows 10 Version 21H2 (build 10.0.19044.0). An attacker with local network access and limited privileges can exploit this flaw to trigger a denial of service, disrupting network communications. The issue is tracked under CWE-131 (Incorrect Calculation of Buffer Size). Microsoft has published an official fix to address this vulnerability.
Potential Impact
The vulnerability allows an authorized attacker on an adjacent network to cause a denial of service (availability impact) by exploiting the incorrect buffer size calculation in the TCP/IP stack. There is no impact on confidentiality or integrity. No known exploits are reported in the wild at this time.
Mitigation Recommendations
An official fix is available from Microsoft. Users and administrators should apply the security update provided in the Microsoft advisory at https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-42915 to remediate this vulnerability.
CVE-2026-42915: CWE-131: Incorrect Calculation of Buffer Size in Microsoft Windows 10 Version 21H2
Description
CVE-2026-42915 is a medium severity vulnerability in Microsoft Windows 10 Version 21H2 caused by incorrect calculation of buffer size in the Windows TCP/IP stack. This flaw allows an authorized attacker on an adjacent network to cause a denial of service condition. The vulnerability does not impact confidentiality or integrity but affects availability. An official fix is available from Microsoft.
CVSS v3.1
Score 5.7medium
Weaknesses
AI-Powered Analysis
Machine-generated threat intelligence
Technical Analysis
This vulnerability (CVE-2026-42915) involves an incorrect calculation of buffer size in the TCP/IP implementation of Windows 10 Version 21H2 (build 10.0.19044.0). An attacker with local network access and limited privileges can exploit this flaw to trigger a denial of service, disrupting network communications. The issue is tracked under CWE-131 (Incorrect Calculation of Buffer Size). Microsoft has published an official fix to address this vulnerability.
Potential Impact
The vulnerability allows an authorized attacker on an adjacent network to cause a denial of service (availability impact) by exploiting the incorrect buffer size calculation in the TCP/IP stack. There is no impact on confidentiality or integrity. No known exploits are reported in the wild at this time.
Mitigation Recommendations
An official fix is available from Microsoft. Users and administrators should apply the security update provided in the Microsoft advisory at https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-42915 to remediate this vulnerability.
Technical Details
- Data Version
- 5.2
- Assigner Short Name
- microsoft
- Date Reserved
- 2026-04-30T22:35:54.969Z
- Cvss Version
- 3.1
- State
- PUBLISHED
- Remediation Level
- official-fix
- Vendor Advisory Urls
- [{"url":"https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-42915","vendor":"Microsoft"}]
Threat ID: 6a284cc48dd33fbd8566481d
Added to database: 6/9/2026, 5:26:28 PM
Last enriched: 6/9/2026, 10:57:27 PM
Last updated: 6/10/2026, 5:11:27 AM
Views: 2
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