SB20260414144 - Multiple vulnerabilities in Microsoft Windows Server Update Service (WSUS)

Description

This security bulletin contains information about 3 vulnerabilities.

1) Input validation error (CVE-ID: CVE-2026-26154)

CWE-ID: CWE-20 - Improper input validation

CVSSv4: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:U/U:Green

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

The vulnerability exists due to insufficient validation of user-supplied input in Windows Server Update Service (WSUS). A remote attacker can pass specially crafted input to the application and perform a denial of service (DoS) attack.

2) Use-after-free (CVE-ID: CVE-2026-32224)

CWE-ID: CWE-416 - Use After Free

CVSSv4: CVSS:4.0/AV:L/AC:L/AT:P/PR:L/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N/E:U/U:Clear

The vulnerability allows a local user to compromise vulnerable system.

The vulnerability exists due to a use-after-free error in Windows Server Update Service (WSUS). A local user can gain elevated privileges on the target system.

3) Race condition (CVE-ID: CVE-2026-26174)

CWE-ID: CWE-362 - Concurrent Execution using Shared Resource with Improper Synchronization ('Race Condition')

CVSSv4: CVSS:4.0/AV:L/AC:L/AT:P/PR:L/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N/E:U/U:Clear

The vulnerability allows a local user to escalate privileges on the system.

The vulnerability exists due to a race condition in Windows Server Update Service (WSUS). A local user can exploit the race and escalate privileges on the system.

Remediation

Install update from vendor's website.

References

• https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-26154
• https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-32224
• https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-26174