Windows Server CVE-2024-43455
CRITICALSeverity by source
AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Network-reachable, unauthenticated licensing service (AV:N/AC:L/PR:N/UI:N); as a spoofing/info-disclosure flaw I weight C:H with limited integrity and no direct availability impact, below NVD's C:H/I:H/A:H.
Primary rating from NVD.
CVSS VectorNVD
Lifecycle Timeline
5DescriptionNVD
Windows Remote Desktop Licensing Service Spoofing Vulnerability
AnalysisAI
Remote unauthenticated attackers can spoof the Windows Remote Desktop Licensing (RD Licensing) Service across all supported Windows Server releases (2008 SP2 through 2022 23H2), per CVE-2024-43455. Although Microsoft classifies it as a spoofing/information-disclosure issue, the assigned CVSS 3.1 vector rates full confidentiality, integrity, and availability impact (9.8), enabling manipulation of the licensing exchange between a client and the RD Licensing server. There is no public exploit identified at time of analysis, but the EPSS score sits in the 90th percentile, and Microsoft has released a patch.
Technical ContextAI
The affected component is the Windows Remote Desktop Licensing (RD Licensing / Terminal Services Licensing) role service, which issues and validates Remote Desktop Services Client Access Licenses (RDS CALs) for RDP session hosts. The root cause is classified as CWE-20 (Improper Input Validation), meaning the service fails to properly validate data received over the network during the licensing protocol exchange, allowing a crafted response or request to impersonate a legitimate party. The CPE data confirms this affects the server operating system layer (cpe:2.3:o:microsoft:windows_server_*) across x86 and x64 variants of Windows Server 2008 SP2, 2008 R2 SP1, 2012, 2012 R2, 2016, 2019, 2022, and 2022 23H2 - indicating a long-standing flaw in a shared RD Licensing code path.
RemediationAI
Patch available per vendor advisory - apply the Microsoft security update for CVE-2024-43455 to each affected Windows Server edition via Windows Update / WSUS; exact per-OS build numbers are listed on the MSRC page at https://msrc.microsoft.com/update-guide/vulnerability/CVE-2024-43455 (patch version not enumerated in the provided input, so confirm the KB for your specific build). Where patching must be delayed, the primary compensating control is to restrict network reachability of the RD Licensing service: place RD Licensing servers behind the firewall and limit the licensing protocol (RPC/TCP 135 and dynamic RPC ports used by Terminal Services Licensing) to only the RD Session Host servers that legitimately request CALs, rather than exposing it broadly - the trade-off is that misconfigured allow-lists can break license issuance and cause RDS grace-period expiry. If the RD Licensing role is not actually required on a given host, uninstalling/disabling the role removes the attack surface entirely, at the cost of that server no longer issuing RDS CALs.
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Same weakness CWE-20 – Improper Input Validation
View allSame technique Information Disclosure
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External POC / Exploit Code
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