EUVD-2025-17772
CVSS Vector
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H
Lifecycle Timeline
3Tags
Description
Use after free in Windows KDC Proxy Service (KPSSVC) allows an unauthorized attacker to execute code over a network.
Analysis
Use-after-free memory corruption vulnerability in Windows KDC Proxy Service (KPSSVC) that allows unauthenticated network attackers to execute arbitrary code with high impact on confidentiality, integrity, and availability. The vulnerability affects Windows systems running the Kerberos KDC Proxy Service and represents a critical remote code execution risk in Active Directory environments. While specific KEV/POC status and EPSS scores are not provided in the source data, the network attack vector combined with high CVSS 8.1 score and remote code execution capability indicates this is a significant priority for organizations relying on Windows authentication infrastructure.
Technical Context
The KDC Proxy Service (KPSSVC) is a Windows component that provides a proxy interface for Kerberos Key Distribution Center (KDC) communications, commonly used in enterprise Active Directory deployments to facilitate Kerberos authentication across network boundaries and firewalls. The vulnerability is rooted in CWE-416 (Use After Free), a memory safety issue where freed memory is accessed after deallocation, potentially allowing attackers to read/write sensitive data or redirect code execution. The use-after-free occurs within the KPSSVC request processing logic, likely in buffer handling or object lifecycle management during Kerberos proxy protocol operations. An attacker can trigger the vulnerability by sending specially crafted network packets that cause premature object deallocation followed by dereferencing, corrupting the heap and achieving code execution in the context of the KPSSVC process (typically SYSTEM privilege on Windows).
Affected Products
Windows KDC Proxy Service (KPSSVC) - specific versions not detailed in provided data. Affected systems typically include: Windows Server 2016, 2019, 2022 editions with KDC Proxy Service role installed or enabled. Enterprise environments using Windows Kerberos authentication with proxy configurations (common in hybrid AD/cloud scenarios). CPE data not provided in source; recommended approach is to query Microsoft Security Updates for CVE-2025-33071 to identify exact KB articles and version/build numbers. Likely affected CPEs would follow pattern: cpe:2.3:o:microsoft:windows_server:*:*:*:*:*:*:*:* with specific version filtering. Consult Microsoft's official security advisory (expected to reference Windows Server 2016 SP2+, 2019, 2022, and potentially Windows 11/10 if KDC Proxy features are enabled).
Remediation
Immediate actions: (1) Apply Microsoft security patch immediately upon release - monitor Microsoft Security Response Center (MSRC) for CVE-2025-33071 KB article; (2) If patching is delayed, disable or restrict network access to KDC Proxy Service ports (typically TCP/UDP 88 for Kerberos, proxy-specific ports per configuration) using firewall rules, limiting exposure to trusted networks only; (3) Implement network segmentation to isolate KDC proxy infrastructure from untrusted zones; (4) Monitor for exploitation attempts targeting KPSSVC process crashes or unusual authentication failures in event logs (Security and System logs, Event ID 4768/4769 for Kerberos events); (5) Escalate patching priority for externally-facing KDC proxy servers in DMZ or hybrid AD scenarios; (6) Once patch is available, test in lab environment before production deployment due to authentication criticality. Vendor advisory links and specific KB numbers will be published by Microsoft - check https://msrc.microsoft.com/ for CVE-2025-33071.
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External POC / Exploit Code
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