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Windows Server 2012Operating system · Microsoft

CVE-2025-49735

HIGH · 8.1 CVSS v3.1 Published 2025-07-08
Fix available
A fix is available. Upgrade to 10.0.14393.8148 / 10.0.17763.7434 or later.
See remediation →
90/100
Remediation priority · Urgent
Remotely reachable No privileges Zero-click

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
Use after free in Windows KDC Proxy Service (KPSSVC) 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

A use-after-free vulnerability exists in the Windows Key Distribution Center Proxy Service (KPSSVC). The flaw allows an unauthenticated remote attacker to execute arbitrary code by exploiting improper memory management in the KDC Proxy Service, which handles Kerberos ticket requests over network connections.

MitigationApply the Microsoft security update for CVE-2025-49735 immediately. If immediate patching is not feasible, consider disabling the KDC Proxy Service if not required, or restricting network access to the service through firewall rules.

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 Server 2012Operating system
Affected:all versions= r2
Windows Server 2016Operating system
Affected:< 10.0.14393.8148
Windows Server 2019Operating system
Affected:< 10.0.17763.7434
Windows Server 2022Operating system
Affected:< 10.0.20348.3807
Windows Server 2022 23h2Operating system
Affected:< 10.0.25398.1665
Windows Server 2025Operating system
Affected:< 10.0.26100.4349

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
High
Privileges
None
User interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High

CVSS:3.1/AV:N/AC:H/PR:N/UI:N/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. Verify KDC Proxy Service is present
    Open Services console (services.msc) or run 'Get-Service -Name KdcProxy' in PowerShell to check if the Key Distribution Center Proxy Service (KdcProxy) is installed on the system.
    Affected if The service does not exist on the system (not affected); if the service exists and is running, proceed to version check.
  2. Check if KDC Proxy Service is running
    Run 'Get-Service -Name KdcProxy | Select-Object Status' in PowerShell or check the Status column in Services console.
    Affected if The service is stopped (not affected); if the service is running, the system could be vulnerable if the version is within the affected range.
  3. Determine Windows Server version
    Run 'winver' or execute 'Get-ComputerInfo | Select-Object OsName, OsVersion' in PowerShell to identify the exact Windows Server version and build number.
    Affected if This check identifies which version range applies to your environment.
  4. Compare installed version against affected ranges
    Run 'systeminfo' or 'Get-ItemProperty HKLM:\SOFTWARE\Microsoft\Windows NT\CurrentVersion' to obtain the full build number (for example, 10.0.14393.8148), then compare against the affected thresholds: Server 2016 < 10.0.14393.8148, Server 2019 < 10.0.17763.7434, Server 2022 < 10.0.20348.3807, Server 2022 23h2 < 10.0.25398.1665, Server 2025 < 10.0.26100.4349.
    Affected if Your installed build number falls below the specified threshold for your Windows Server version.

You are affected if the KDC Proxy Service is running and your Windows Server build number is below the threshold for your version (2016 < 10.0.14393.8148, 2019 < 10.0.17763.7434, 2022 < 10.0.20348.3807, 2022 23h2 < 10.0.25398.1665, 2025 < 10.0.26100.4349); Server 2012 R2 is fully affected as all versions are vulnerable.

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 10.0.14393.8148 / 10.0.17763.7434 / 10.0.20348.3807 or later
Fixed in 10.0.14393.814810.0.17763.743410.0.20348.3807
Interim mitigation

Apply the Microsoft security update for CVE-2025-49735 immediately. If immediate patching is not feasible, consider disabling the KDC Proxy Service if not required, or restricting network access to the service through firewall rules.

Recommended fix High confidence

Apply the corresponding cumulative security update from Microsoft for your Windows Server version (e.g., KBxxxxxx for your specific Windows Server release)

  1. Identify the current Windows Server version by running 'winver' or 'systeminfo' in Command Prompt
  2. Determine the appropriate KB patch by checking Microsoft Security Response Center (msrc.microsoft.com) for CVE-2025-49735
  3. For Windows Server 2016: apply update to reach build 10.0.14393.8148 or later
  4. For Windows Server 2019: apply update to reach build 10.0.17763.7434 or later
  5. For Windows Server 2022: apply update to reach build 10.0.20348.3807 or later
  6. For Windows Server 2022 23h2: apply update to reach build 10.0.25398.1665 or later
  7. For Windows Server 2025: apply update to reach build 10.0.26100.4349 or later
  8. For Windows Server 2012/2012 R2: no patch available - migrate to a supported Windows Server version as these releases reached end of support
Caveat Windows Server 2012/2012 R2 has no patch available; migration to supported OS required (end of support since October 2023)

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

Fix this in Windows Server 2012 Scoped from the published advisory
  • Consultation2.0 h
  • Implementation3.0 h
  • Testing4.0 h
  • Review / QA2.0 h
11.0 hours of engineering $1,900
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Scan for this in your stack

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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-2025-49735 in production — separate from our analysis above.

No notes yet

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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