Multiple vulnerabilities in Microsoft Windows Telephony Service

1) Heap-based buffer overflow

EUVDB-ID: #VU103785

Risk: High

CVSSv4.0: 6.1 [CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:A/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N/E:U/U:Amber]

CVE-ID: CVE-2025-21200

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

Exploit availability: No

Description

The vulnerability allows a remote attacker to execute arbitrary code on the target system.

The vulnerability exists due to a boundary error in Windows Telephony Service. A remote attacker can trick a victim to connect to a malicious server, trigger a heap-based buffer overflow and execute arbitrary code on the target system.

Successful exploitation of this vulnerability may result in complete compromise of vulnerable system.

Mitigation

Install updates from vendor's website.

Vulnerable software versions

Windows: 10 21H2 10.0.19041.3920 - 11 24H2 10.0.26100.2894

Windows Server: 2008 R2 6.1.7601.27067 - 2025 10.0.26100.2894

CPE2.3

External links

https://portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2025-21200

Q & A

Can this vulnerability be exploited remotely?

Yes. This vulnerability can be exploited by a remote non-authenticated attacker via the Internet.

Is there known malware, which exploits this vulnerability?

No. We are not aware of malware exploiting this vulnerability.

2) Heap-based buffer overflow

EUVDB-ID: #VU103789

Risk: High

CVSSv4.0: 6.1 [CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:A/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N/E:U/U:Amber]

CVE-ID: CVE-2025-21407

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

Exploit availability: No

Description

The vulnerability allows a remote attacker to execute arbitrary code on the target system.

The vulnerability exists due to a boundary error in Windows Telephony Service. A remote attacker can trick a victim to connect to a malicious server, trigger a heap-based buffer overflow and execute arbitrary code on the target system.

Successful exploitation of this vulnerability may result in complete compromise of vulnerable system.

Mitigation

Install updates from vendor's website.

Vulnerable software versions

Windows: 10 21H2 10.0.19041.3920 - 11 24H2 10.0.26100.2894

Windows Server: 2008 R2 6.1.7601.27067 - 2025 10.0.26100.2894

CPE2.3

External links

https://portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2025-21407

Q & A

Can this vulnerability be exploited remotely?

Yes. This vulnerability can be exploited by a remote non-authenticated attacker via the Internet.

Is there known malware, which exploits this vulnerability?

No. We are not aware of malware exploiting this vulnerability.

3) Heap-based buffer overflow

EUVDB-ID: #VU103788

Risk: High

CVSSv4.0: 6.1 [CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:A/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N/E:U/U:Amber]

CVE-ID: CVE-2025-21371

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

Exploit availability: No

Description

The vulnerability allows a remote attacker to execute arbitrary code on the target system.

The vulnerability exists due to a boundary error in Windows Telephony Service. A remote attacker can trick a victim to connect to a malicious server, trigger a heap-based buffer overflow and execute arbitrary code on the target system.

Successful exploitation of this vulnerability may result in complete compromise of vulnerable system.

Mitigation

Install updates from vendor's website.

Vulnerable software versions

Windows: 10 21H2 10.0.19041.3920 - 11 24H2 10.0.26100.2894

Windows Server: 2008 R2 6.1.7601.27067 - 2025 10.0.26100.2894

CPE2.3

External links

https://portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2025-21371

Q & A

Can this vulnerability be exploited remotely?

Yes. This vulnerability can be exploited by a remote non-authenticated attacker via the Internet.

Is there known malware, which exploits this vulnerability?

No. We are not aware of malware exploiting this vulnerability.

4) Heap-based buffer overflow

EUVDB-ID: #VU103787

Risk: High

CVSSv4.0: 6.1 [CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:A/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N/E:U/U:Amber]

CVE-ID: CVE-2025-21190

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

Exploit availability: No

Description

The vulnerability allows a remote attacker to execute arbitrary code on the target system.

The vulnerability exists due to a boundary error in Windows Telephony Service. A remote attacker can trick a victim to connect to a malicious server, trigger a heap-based buffer overflow and execute arbitrary code on the target system.

Successful exploitation of this vulnerability may result in complete compromise of vulnerable system.

Mitigation

Install updates from vendor's website.

Vulnerable software versions

Windows: 10 21H2 10.0.19041.3920 - 11 24H2 10.0.26100.2894

Windows Server: 2008 R2 6.1.7601.27067 - 2025 10.0.26100.2894

CPE2.3

External links

https://portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2025-21190

Q & A

Can this vulnerability be exploited remotely?

Yes. This vulnerability can be exploited by a remote non-authenticated attacker via the Internet.

Is there known malware, which exploits this vulnerability?

No. We are not aware of malware exploiting this vulnerability.

5) Use-after-free

EUVDB-ID: #VU103786

Risk: High

CVSSv4.0: 6.1 [CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:A/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N/E:U/U:Amber]

CVE-ID: CVE-2025-21406

CWE-ID: CWE-416 - Use After Free

Exploit availability: No

Description

The vulnerability allows a remote attacker to compromise vulnerable system.

The vulnerability exists due to a use-after-free error in Windows Telephony Service. A remote attacker can trick a victim to connect to a malicious server and execute arbitrary code on the target system.

Mitigation

Install updates from vendor's website.

Vulnerable software versions

Windows: 10 21H2 10.0.19041.3920 - 11 24H2 10.0.26100.2894

Windows Server: 2008 R2 6.1.7601.27067 - 2025 10.0.26100.2894

CPE2.3

External links

https://portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2025-21406

Q & A

Can this vulnerability be exploited remotely?

Yes. This vulnerability can be exploited by a remote non-authenticated attacker via the Internet.

Is there known malware, which exploits this vulnerability?

No. We are not aware of malware exploiting this vulnerability.

Risk	High
Patch available	YES
Number of vulnerabilities	5
CVE-ID	CVE-2025-21200 CVE-2025-21407 CVE-2025-21371 CVE-2025-21190 CVE-2025-21406
CWE-ID	CWE-122 CWE-416
Exploitation vector	Network
Public exploit	N/A
Vulnerable software	Windows Operating systems & Components / Operating system Windows Server Operating systems & Components / Operating system
Vendor	Microsoft