dbcve.org
Windows 10 1507Operating system · Microsoft

CVE-2025-21205

HIGH · 8.8 CVSS v3.1 Published 2025-04-08
Fix available
A fix is available. Upgrade to 10.0.10240.20978 / 10.0.14393.7969 or later.
See remediation →
95/100
Remediation priority · Urgent
Remotely reachable No privileges

Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.

NVD · unedited
Heap-based buffer overflow in Windows Telephony Service allows an unauthorized attacker to execute code over a network.

Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.

dbcve analysis · moderate confidence

Heap-based buffer overflow vulnerability in Windows Telephony Service that allows an unauthorized remote attacker to execute arbitrary code. The vulnerability is network-exploitable and affects the Windows Telephony Service component.

MitigationApply Microsoft security updates for CVE-2025-21205 when released. Prioritize patching exposed Windows servers and workstations running Telephony Service. Implement network segmentation and firewall rules to limit exposure to untrusted networks as an interim control.

Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.

Affected products & versions What the vendor confirmedThe version ranges the vendor confirmed as vulnerable. If your version sits inside a range here, treat yourself as exposed until you have upgraded.

NVD · CPE data
Windows 10 1507Operating system
Affected:< 10.0.10240.20978
Windows 10 1607Operating system
Affected:< 10.0.14393.7969
Windows 10 1809Operating system
Affected:< 10.0.17763.7136
Windows 10 21h2Operating system
Affected:< 10.0.19044.5737
Windows 10 22h2Operating system
Affected:< 10.0.19045.5737
Windows 11 22h2Operating system
Affected:< 10.0.22621.5189
Windows 11 23h2Operating system
Affected:< 10.0.22631.5189
Windows 11 24h2Operating system
Affected:< 10.0.26100.3775

CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.

From the vector
Attack vector
Network
Complexity
Low
Privileges
None
User interaction
Required
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High

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

Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.

dbcve checks

Work through these to decide whether this CVE applies to you.

  1. Check Windows version and build number
    Open Command Prompt or PowerShell and run: `winver` or `systeminfo | findstr /B /C:"OS Name" /C:"OS Version"`. Alternatively, run `winver` to display the full Windows version dialog.
    Affected if The displayed build number falls below the safe threshold for your Windows release (1507: 10240.20978, 1607: 14393.7969, 1809: 17763.7136, 21h2: 19044.5737, 22h2: 19045.5737, 11 22h2: 22621.5189, 11 23h2: 22631.5189, 11 24h2: 26100.3775).
  2. Verify Telephony Service status
    Open Services (services.msc) and locate "Telephony" service, or run `Get-Service -Name PhoneSvc` in PowerShell. Also check via command line: `sc query PhoneSvc`.
    Affected if The Telephony service (PhoneSvc) is installed and running on the system.
  3. Confirm Windows edition includes Telephony component
    Check if the Windows edition supports Telephony Service. Run `Get-WindowsOptionalFeature -Online | Where-Object {$_.FeatureName -like "*Telephony*"}` in PowerShell to list telephony-related features.
    Affected if Telephony features or the PhoneSvc service are present on the system.

Your system is affected if it runs a Windows version with a build number lower than the safe threshold AND has the Telephony Service (PhoneSvc) enabled or installed.

Generated from the published advisory. Verify against your own configuration.

Check your environment

Paste your version and any relevant configuration and it will be compared against the affected criteria above. Do not include secrets or credentials.

AI-assisted, checked against the advisory. Informational, not a guarantee.

Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.

dbcve · scoped
Upgrade available Upgrade to 10.0.10240.20978 / 10.0.14393.7969 / 10.0.17763.7136 or later
Fixed in 10.0.10240.2097810.0.14393.796910.0.17763.7136
Interim mitigation

Apply Microsoft security updates for CVE-2025-21205 when released. Prioritize patching exposed Windows servers and workstations running Telephony Service. Implement network segmentation and firewall rules to limit exposure to untrusted networks as an interim control.

Recommended fix High confidence

Apply Microsoft security update KB5002537 or subsequent cumulative update containing the fix for CVE-2025-21205; specific fixed builds: Windows 10 1507 (10.0.10240.20978), Windows 10 1607 (10.0.14393.7969), Windows 10 1809 (10.0.17763.7136), Windows 10 21h2 (10.0.19044.5737), Windows 10 22h2 (10.0.1

  1. Open Windows Update by pressing Win + I and navigating to Update & Security > Windows Update
  2. Click 'Check for updates' to download and install the latest security updates
  3. Alternatively, manually download the specific security update for CVE-2025-21205 from the Microsoft Update Catalog (catalog.update.microsoft.com)
  4. Restart the system after installing the update
  5. Verify the update was installed by checking Windows Update history or running 'winver' to confirm the build number matches or exceeds the fixed version for your Windows release
Caveat Standard Windows cumulative update; no expected breaking changes for this security patch

Generated from the published advisory — verify against the referenced sources before acting.

Fix this in Windows 10 1507 Scoped from the published advisory
  • Consultation6.0 h
  • Implementation12.0 h
  • Testing8.0 h
  • Review / QA4.0 h
30.0 hours of engineering $5,280
Get the upgrade done

An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $8,448.

Scan for this in your stack

Free · runs locally
dbcve dependency scanner

Check whether your project pulls in CVE-2025-21205 — or any other known-vulnerable package — straight from your lock files. Free and open source; it runs locally and uploads nothing.

Get it on GitHub Scan in the browser

References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2025-21205 in production — separate from our analysis above.

No notes yet

Be the first to add a field note for this CVE — a mitigation you’ve verified, a version caveat, or a link to a working fix. Sign in above to contribute.

What this is

A place for practitioners to share what actually worked: a mitigation you’ve tested, a configuration change, a version- or environment-specific caveat, or a link to a verified patch. The most useful notes rise to the top as peers upvote them, so the signal stays high.

What belongs here
  • Verified mitigations, workarounds, and config changes
  • Version or environment caveats, and links to real fixes
  • No weaponised exploit code, or anything meant to cause harm
  • No spam, self-promotion, credentials, or personal data