SB2026071504 - Multiple vulnerabilities in Microsoft Windows DNS Client

Description

This security bulletin contains information about 3 vulnerabilities.

1) Improper access control (CVE-ID: CVE-2026-50465)

CWE-ID: CWE-284 - Improper Access Control

CVSSv4: 6.9 [CVSS:4.0/AV:L/AC:L/AT:N/PR:L/UI:N/VC:N/VI:H/VA:H/SC:N/SI:N/SA:N]

The vulnerability allows a local user to gain unauthorized access to otherwise restricted functionality.

The vulnerability exists due to improper access restrictions in Windows DNS Client. A local user can bypass implemented security restrictions and perform tampering attack.

2) Use-after-free (CVE-ID: CVE-2026-50487)

CWE-ID: CWE-416 - Use After Free

CVSSv4: 9.2 [CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N]

The vulnerability allows a remote attacker to compromise vulnerable system.

The vulnerability exists due to a use-after-free error in Windows DNS Client. A remote attacker can gain elevated privileges on the target system.

3) Heap-based buffer overflow (CVE-ID: CVE-2026-49175)

CWE-ID: CWE-122 - Heap-based Buffer Overflow

CVSSv4: 8.5 [CVSS:4.0/AV:L/AC:L/AT:N/PR:L/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N]

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

The vulnerability exists due to a boundary error in Windows DNS Client. A local user can pass specially crafted data to the application, trigger a heap-based buffer overflow and gain elevated privileges on the system.

Remediation

Install update from vendor's website.

References

• https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-50465
• https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-50487
• https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-49175