SB20260512124 - Multiple vulnerabilities in Microsoft Windows Telephony Service

Description

This security bulletin contains information about 3 vulnerabilities.

1) Use-after-free (CVE-ID: CVE-2026-34338)

CWE-ID: CWE-416 - Use After Free

CVSSv4: 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/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 Telephony Service. A local user can gain elevated privileges on the target system.

2) Use-after-free (CVE-ID: CVE-2026-42825)

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 Telephony Service. A local user can win a race condition and gain elevated privileges on the target system.

3) Use-after-free (CVE-ID: CVE-2026-40382)

CWE-ID: CWE-416 - Use After Free

CVSSv4: 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/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 Telephony Service. A local user can gain elevated privileges on the target system.

Remediation

Install update from vendor's website.

References

• https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-34338
• https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-42825
• https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-40382