Incorrect Calculation of Buffer Size in Microsoft Windows and Windows Server - CVE-2026-42915

Vulnerability identifier: #VU134356

CSH Severity: Medium

CVSS v4: 6.9 [CVSS:4.0/AV:A/AC:L/AT:N/PR:L/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N]

CVE-ID: CVE-2026-42915

CWE-ID: CWE-131

Exploitation vector: Adjecent network

Exploit availability: No public exploit available

The vulnerability allows a remote attacker to perform a denial of service (DoS) attack.

The vulnerability exists due to a boundary error in Windows TCP/IP. A remote user on the local network can trigger memory corruption and cause a denial of service condition on the target system.

Microsoft Windows
Windows Server

Install updates from vendor's website.

Microsoft Windows - addressed in versions 10 21H2 10.0.19044.7417, 10 22H2 10.0.19045.7417, 10 1607 10.0.14393.9234, 11 23H2 10.0.22631.7219, 11 24H2 10.0.26100.8655, 11 25H2 10.0.26200.8655, 11 26H1 10.0.28000.2269
Windows Server - addressed in versions 2022 10.0.20348.5256, 2025 10.0.26100.8655, 2025 10.0.26100.32995

• https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-42915

• Multiple vulnerabilities in Microsoft Windows TCP/IP