CVE-2025-53154 Overview
CVE-2025-53154 is a null pointer dereference vulnerability [CWE-476] in the Windows Ancillary Function Driver for WinSock (afd.sys). The flaw allows an authorized local attacker to elevate privileges on affected Windows systems. Microsoft addressed the issue in its August 2025 security update cycle.
The vulnerability affects a broad range of supported Windows client and server versions, from Windows 10 1507 through Windows 11 24H2, and from Windows Server 2008 through Windows Server 2025. Successful exploitation grants an attacker code execution in kernel context, resulting in full compromise of confidentiality, integrity, and availability on the local host.
Critical Impact
A locally authenticated attacker can trigger a null pointer dereference in afd.sys to escalate from a standard user account to SYSTEM-level privileges.
Affected Products
- Microsoft Windows 10 (1507, 1607, 1809, 21H2, 22H2)
- Microsoft Windows 11 (22H2, 23H2, 24H2)
- Microsoft Windows Server 2008, 2012, 2016, 2019, 2022, 2022 23H2, and 2025
Discovery Timeline
- 2025-08-12 - CVE-2025-53154 published to NVD and Microsoft releases security patch
- 2026-06-17 - Last updated in NVD database
Technical Details for CVE-2025-53154
Vulnerability Analysis
The Ancillary Function Driver for WinSock (afd.sys) is a kernel-mode driver that provides the transport interface between user-mode WinSock applications and lower-level TCP/IP components. Because it processes I/O request packets (IRPs) originating from any local process, afd.sys has long been a favored target for local privilege escalation research.
CVE-2025-53154 is a null pointer dereference triggered when the driver operates on a pointer that has not been validated before use. On modern Windows builds, a local attacker with the ability to allocate memory at low addresses or manipulate the referenced object state can convert this dereference into arbitrary kernel read/write primitives, leading to privilege escalation.
Exploitation requires local access and low privileges but no user interaction. The scope is unchanged, meaning the impact is confined to the affected host, however the resulting SYSTEM-level access provides full control of that machine.
Root Cause
The root cause is missing validation of a pointer within a code path in afd.sys reachable from user-mode DeviceIoControl calls against the \Device\Afd device object. When the object referenced by the pointer is absent or in an unexpected state, the driver dereferences a NULL value in kernel context, classified as [CWE-476].
Attack Vector
The attack vector is local. An attacker executes code as a standard user, opens a handle to the AFD device, and issues a crafted sequence of I/O control requests to reach the vulnerable path. By pairing the dereference with a controlled kernel object placement technique, an attacker can hijack execution flow and overwrite process tokens to gain SYSTEM privileges. Public exploitation details for CVE-2025-53154 have not been released, and the vulnerability is not listed in the CISA Known Exploited Vulnerabilities catalog. Refer to the Microsoft Security Update Guide for authoritative technical details.
Detection Methods for CVE-2025-53154
Indicators of Compromise
- Unexpected child processes of low-privileged user sessions running with NT AUTHORITY\SYSTEM integrity.
- Kernel bugcheck events referencing afd.sys (for example, Stop 0x0000003B or 0x00000050) followed by suspicious process activity after reboot.
- New service, scheduled task, or driver installations shortly after a local user session opens a handle to \Device\Afd.
Detection Strategies
- Hunt for token manipulation patterns where a non-administrative process suddenly acquires SYSTEM privileges without a legitimate parent such as services.exe.
- Correlate WinSock-related handle opens with subsequent creation of privileged processes from the same PID lineage.
- Monitor Windows Error Reporting and crash dumps for repeated afd.sys faults, which can indicate exploit development or unstable exploitation attempts.
Monitoring Recommendations
- Ingest Sysmon Event ID 1 (process creation) and Event ID 10 (process access) to track privilege transitions and access to lsass.exe from unexpected callers.
- Enable kernel-mode auditing and forward crash telemetry to a centralized data lake for cross-host correlation.
- Alert on installation of unsigned or newly observed drivers on endpoints running vulnerable Windows builds.
How to Mitigate CVE-2025-53154
Immediate Actions Required
- Apply the August 2025 Microsoft security update that patches afd.sys on every affected Windows client and server SKU.
- Prioritize patching multi-user systems, jump hosts, terminal servers, and any endpoint where non-administrative users execute untrusted code.
- Inventory legacy hosts running Windows Server 2008 or 2012 and confirm Extended Security Update coverage is active before deploying the fix.
Patch Information
Microsoft released fixes for CVE-2025-53154 through its standard monthly cumulative updates. Administrators should consult the Microsoft Security Update Guide entry for CVE-2025-53154 to identify the specific KB article for each supported Windows version and deploy through Windows Update, WSUS, Intune, or Configuration Manager.
Workarounds
- No official workaround eliminates the vulnerability; patching is the only supported remediation.
- Reduce exposure by enforcing least privilege, restricting local logon rights, and blocking execution of untrusted binaries via Windows Defender Application Control or AppLocker.
- Apply attack surface reduction rules and Credential Guard to limit post-exploitation impact if a local user account is compromised.
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
