CVE-2025-21201Network attack vector

Remote code execution via undisclosed double free

Published Feb 11, 2025 · Updated Feb 26, 2026

Double free in Windows Telephony Server allows remote attackers to execute code by persuading a user to connect to a malicious server. Microsoft identifies CWE-415 but has not disclosed the affected function, freed object, or operation that releases it twice. Exploitation requires user interaction and can execute code in the context of the affected Telephony Server process.

CVSS severity8.8
High
EPSS probability1.83%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Double free in Windows Telephony Server allows remote attackers to execute code by persuading a user to connect to a malicious server. Microsoft identifies CWE-415 but has not disclosed the affected function, freed object, or operation that releases it twice. Exploitation requires user interaction and can execute code in the context of the affected Telephony Server process.

The record

CVE
CVE-2025-21201
Published
Feb 11, 2025
Updated
Feb 26, 2026
Vendor
Microsoft
Product
Windows 10 Version 1507
Classifications
CWE-415, T1203
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Feb 11, 2025CVE publishedPublication date reported by the CVE source.
  2. Feb 26, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

Compare your product and version with the public record. A matching version still requires validation against your environment.

Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=10.0.10240.0 <10.0.10240.20915

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Microsoft · Windows 10 Version 1507version=10.0.10240.0 <10.0.10240.20915
Microsoft · Windows Server 2019version=10.0.17763.0 <10.0.17763.6893
Microsoft · Windows Server 2025 (Server Core installation)version=10.0.26100.0 <10.0.26100.3194
Microsoft · Windows Server 2016 (Server Core installation)version=10.0.14393.0 <10.0.14393.7785
Microsoft · Windows 11, version 24H2version=10.0.26100.0 <10.0.26100.3194
Microsoft · Windows Server 2012 (Server Core installation)version=6.2.9200.0 <6.2.9200.25317
Microsoft · Windows Server 2012version=6.2.9200.0 <6.2.9200.25317
Microsoft · Windows 10 Version 21H2version=10.0.19044.0 <10.0.19044.5487
Microsoft · Windows Server 2022, 23H2 Edition (Server Core installation)version=10.0.25398.0 <10.0.25398.1425
Microsoft · Windows Server 2016version=10.0.14393.0 <10.0.14393.7785
Microsoft · Windows 11 Version 22H3version=10.0.22631.0 <10.0.22631.4890
Microsoft · Windows Server 2008 R2 Service Pack 1version=6.1.7601.0 <6.1.7601.27566
Microsoft · Windows Server 2008 R2 Service Pack 1 (Server Core installation)version=6.1.7601.0 <6.1.7601.27566
Microsoft · Windows 10 Version 22H2version=10.0.19045.0 <10.0.19045.5487
Microsoft · Windows Server 2012 R2 (Server Core installation)version=6.3.9600.0 <6.3.9600.22417
Microsoft · Windows Server 2019 (Server Core installation)version=10.0.17763.0 <10.0.17763.6893
Microsoft · Windows 11 Version 23H2version=10.0.22631.0 <10.0.22631.4890
Microsoft · Windows 11, version 22H2version=10.0.22621.0 <10.0.22621.4890
Microsoft · Windows 10 Version 1607version=10.0.14393.0 <10.0.14393.7785
Microsoft · Windows Server 2008 Service Pack 2version=6.0.6003.0 <6.0.6003.23117
Microsoft · Windows Server 2022version=10.0.20348.0 <10.0.20348.3207
Microsoft · Windows Server 2025version=10.0.26100.0 <10.0.26100.3194
Microsoft · Windows 10 Version 1809version=10.0.17763.0 <10.0.17763.6893
Microsoft · Windows Server 2012 R2version=6.3.9600.0 <6.3.9600.22417
Microsoft · Windows Server 2008 Service Pack 2 (Server Core installation)version=6.0.6003.0 <6.0.6003.23117

Published CVSS scores

8.8MicrosoftCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-415Double Free
T1203Exploitation for Client Execution

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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