CriticalCVE-2025-32709

    Windows Ancillary Function Driver for WinSock Elevation of Privilege Vulnerability (CVE-2025-32709)

    Published In CISA KEV since Sources: pwn.watch, CVE.org, Msrc Update Guide

    What is affected, what to do

    Null pointer dereference in Windows Ancillary Function Driver for WinSock allows an authorized attacker to elevate privileges locally.

    The vulnerability is being actively exploited; treat it as a priority. Update Microsoft Windows 10 Version 1507 to version 10.0.10240.21014, Microsoft Windows 10 Version 1607 to version 10.0.14393.8066, Microsoft Windows 10 Version 1809 to version 10.0.17763.7314. Immediate actions, mitigation and detection rules are in the runbook below.

    Affected
    • Microsoft Windows 10 Version 1507 lt 10.0.10240.0..10.0.10240.21014
    • Microsoft Windows 10 Version 1607 lt 10.0.14393.0..10.0.14393.8066
    • Microsoft Windows 10 Version 1809 lt 10.0.17763.0..10.0.17763.7314
    • Microsoft Windows 10 Version 21H2 lt 10.0.19044.0..10.0.19044.5854
    • Microsoft Windows 10 Version 22H2 lt 10.0.19045.0..10.0.19045.5854
    • Microsoft Windows 11 version 22H2 lt 10.0.22621.0..10.0.22621.5335
    • Microsoft Windows 11 version 22H3 lt 10.0.22631.0..10.0.22631.5335
    • Microsoft Windows 11 Version 23H2 lt 10.0.22631.0..10.0.22631.5335
    • Microsoft Windows 11 Version 24H2 lt 10.0.26100.0..10.0.26100.4061
    • Microsoft Windows Server 2008 R2 Service Pack 1 lt 6.1.7601.0..6.1.7601.27730
    • Microsoft Windows Server 2008 R2 Service Pack 1 (Server Core installation) lt 6.1.7601.0..6.1.7601.27730
    • Microsoft Windows Server 2008 Service Pack 2 lt 6.0.6003.0..6.0.6003.23317
    • Microsoft Windows Server 2008 Service Pack 2 (Server Core installation) lt 6.0.6003.0..6.0.6003.23317
    • Microsoft Windows Server 2012 lt 6.2.9200.0..6.2.9200.25475
    • Microsoft Windows Server 2012 (Server Core installation) lt 6.2.9200.0..6.2.9200.25475
    • Microsoft Windows Server 2012 R2 lt 6.3.9600.0..6.3.9600.22577
    • Microsoft Windows Server 2012 R2 (Server Core installation) lt 6.3.9600.0..6.3.9600.22577
    • Microsoft Windows Server 2016 lt 10.0.14393.0..10.0.14393.8066
    • Microsoft Windows Server 2016 (Server Core installation) lt 10.0.14393.0..10.0.14393.8066
    • Microsoft Windows Server 2019 lt 10.0.17763.0..10.0.17763.7314
    • Microsoft Windows Server 2019 (Server Core installation) lt 10.0.17763.0..10.0.17763.7314
    • Microsoft Windows Server 2022 lt 10.0.20348.0..10.0.20348.3692
    • Microsoft Windows Server 2022, 23H2 Edition (Server Core installation) lt 10.0.25398.0..10.0.25398.1611
    • Microsoft Windows Server 2025 lt 10.0.26100.0..10.0.26100.4061
    • Microsoft Windows Server 2025 (Server Core installation) lt 10.0.26100.0..10.0.26100.4061
    Fixed in
    • Microsoft Windows 10 Version 1507 10.0.10240.21014
    • Microsoft Windows 10 Version 1607 10.0.14393.8066
    • Microsoft Windows 10 Version 1809 10.0.17763.7314
    • Microsoft Windows 10 Version 21H2 10.0.19044.5854
    • Microsoft Windows 10 Version 22H2 10.0.19045.5854
    • Microsoft Windows 11 version 22H2 10.0.22621.5335
    • Microsoft Windows 11 version 22H3 10.0.22631.5335
    • Microsoft Windows 11 Version 23H2 10.0.22631.5335
    • Microsoft Windows 11 Version 24H2 10.0.26100.4061
    • Microsoft Windows Server 2008 R2 Service Pack 1 6.1.7601.27730
    • Microsoft Windows Server 2008 R2 Service Pack 1 (Server Core installation) 6.1.7601.27730
    • Microsoft Windows Server 2008 Service Pack 2 6.0.6003.23317
    • Microsoft Windows Server 2008 Service Pack 2 (Server Core installation) 6.0.6003.23317
    • Microsoft Windows Server 2012 6.2.9200.25475
    • Microsoft Windows Server 2012 (Server Core installation) 6.2.9200.25475
    • Microsoft Windows Server 2012 R2 6.3.9600.22577
    • Microsoft Windows Server 2012 R2 (Server Core installation) 6.3.9600.22577
    • Microsoft Windows Server 2016 10.0.14393.8066
    • Microsoft Windows Server 2016 (Server Core installation) 10.0.14393.8066
    • Microsoft Windows Server 2019 10.0.17763.7314
    • Microsoft Windows Server 2019 (Server Core installation) 10.0.17763.7314
    • Microsoft Windows Server 2022 10.0.20348.3692
    • Microsoft Windows Server 2022, 23H2 Edition (Server Core installation) 10.0.25398.1611
    • Microsoft Windows Server 2025 10.0.26100.4061
    • Microsoft Windows Server 2025 (Server Core installation) 10.0.26100.4061

    Not sure whether and how you are affected? Ask a question about this vulnerability

    Metrics

    7.8

    Priority

    XIEM Effective CVSS: highest available CVSS rating from NVD and vendor data.

    Source: NVD, CVSS v3

    7.8

    CVSS v3

    Severity High on the scale from 0 to 10.

    Source: pwn.watch, CVE.org, Msrc Update Guide

    1.8 %

    EPSS score

    Moderate — model estimates 1-10% exploitation likelihood.

    Source: FIRST EPSS, percentile 78.6

    Show all metrics
    Severity
    Critical
    Priority (0–325)

    The priority score is a consolidated metric that condenses several individual signals into a single, action-guiding ranking: technical severity (CVSS), exploitation likelihood (EPSS), known-exploited status (KEV) and the context of the affected asset. The aim is to answer the only truly important question in vulnerability management: what first?

    Read in glossary
    197.39 Methodology
    Exploit maturity

    An exploit is code or a technique that specifically uses a concrete vulnerability to force unintended behaviour — such as executing code or escalating privileges. It is the tool that turns a theoretical flaw into a practical attack.

    Read in glossary
    actively exploitedSource: VulnCheck KEV (opens in a new tab) How we classify
    XIEM Effective CVSS

    XIEM® is the tiered managed-security operating model from NEOSEC and a registered trademark of NEOSEC GmbH. It extends classic SIEM — the central collection, normalisation and correlation of security-relevant events — with endpoint forensics, network visibility and deception technology, and consolidates them into three building tiers: Sentry, Orchestrate and Command.

    Read in glossary
    7.8 Methodology
    CVSS v3

    CVSS is the globally established, open standard for assessing the technical severity of a vulnerability on a scale from 0 to 10. It describes how easily a flaw can be exploited and what damage it can cause — but not how likely its actual exploitation is. CVSS and the complementary EPSS deliberately answer different questions.

    Read in glossary
    7.8
    EPSS score

    The EPSS score is the absolute model output for an individual vulnerability: the estimated probability of real-world exploitation within the next 30 days, expressed as a value between 0 and 1 (i.e. 0 % to 100 %). A score of 0.42 means „the model estimates a 42 % chance of real-world exploitation within 30 days“.

    Read in glossary
    1.8 %
    Moderate — model estimates 1-10% exploitation likelihood.
    EPSS percentile

    The EPSS percentile is the relative position of a vulnerability within all EPSS-scored CVEs, expressed as a value between 0 and 1. A percentile of 0.90 means „this CVE has a higher EPSS score than 90 % of all other scored CVEs“. Unlike the EPSS score, it is not a probability — but a positioning within a ranking.

    Read in glossary
    78.6
    High — this CVE ranks above the median of all CVEs scored today (rank ≥ 36%).
    KEV status

    The KEV catalogue is a list maintained by the US authority CISA of vulnerabilities for which active exploitation in the wild has been confirmed. It answers not the question „how severe?“ but „is it already being attacked?“ — thereby sharply prioritising patching.

    Read in glossary
    Actively exploited
    Published
    In CISA KEV since

    The KEV catalogue is a list maintained by the US authority CISA of vulnerabilities for which active exploitation in the wild has been confirmed. It answers not the question „how severe?“ but „is it already being attacked?“ — thereby sharply prioritising patching.

    Read in glossary
    CWE

    CWE is a catalogue of typical weakness types in software and hardware — such as flawed input validation, unsafe memory handling or poor authentication. Where a CVE names a concrete vulnerability in a concrete product, a CWE describes the underlying class of defect.

    Read in glossary
    CWE-416

    Response and mitigation

    Why act now?

    Prioritisation rationale

    This is a classic post-exploitation building block. It requires existing low-privileged local code execution, needs no user interaction and gives low-complexity, full system control. Attackers therefore chain it after phishing or account compromise to kill security tooling and harvest credentials for lateral movement. Note that CISA describes the flaw as a use-after-free while NVD calls it a null pointer dereference; the patching requirement is the same either way. Exploitation likelihood is generally rated moderate, and CISA reports no known ransomware use, but treat multi-user and admin systems as high priority and patch them within days, with the remaining client fleet on an accelerated regular cycle.

    1. Runbook step 1

      Immediate response (0-24 h)

      • Deploy the May 2025 cumulative security update. Target builds per the advisory: Windows 10 1507 ≥ 10.0.10240.21014, 1607 ≥ 10.0.14393.8066, 1809 ≥ 10.0.17763.7314, 21H2/22H2 ≥ 10.0.19044.5854 / 10.0.19045.5854, Windows 11 22H2 ≥ 10.0.22621.5335, 22H3/23H2 ≥ 10.0.22631.5335. Look up the per-build KB numbers in the Microsoft advisory. Check server editions sharing a build base (14393, 17763) and unlisted versions (e.g. Windows 11 24H2) against the vendor advisory.
      • Build a build inventory via MDM/SCCM/Intune. Query CurrentBuild.UBR from HKLM\SOFTWARE\Microsoft\Windows NT\CurrentVersion and flag every host below its target build as exposed.
      • Patch multi-user systems first. This means RDS/Citrix hosts, VDI pools, jump hosts, admin workstations and kiosks. Many low-privileged accounts have local code execution on these systems, and a SYSTEM escalation immediately exposes other users' sessions and cached credentials.
      • Identify hosts that cannot be patched. This covers EOL builds and LTSB/LTSC releases no longer eligible for ESU. Move them into a restricted segment and limit interactive logon to named administrators.
      • Run a retrospective hunt for privilege escalation (see detection rules) back to at least early May 2025. If exploitation is confirmed on NIS2/KRITIS-relevant assets, assess the reporting obligation (early warning within 24 h).

    2. Runbook step 2

      Mitigation layers

      • Configuration: There is no practical workaround for afd.sys. It is a core part of the Winsock stack and cannot be disabled. Compensating controls therefore have to make local foothold and code execution harder.
      • Application control: Deploy WDAC or AppLocker policies that block unsigned binaries from user-writable paths (%AppData%, %Temp%, %LocalAppData%, C:\Users\Public, C:\ProgramData). Local privilege-escalation exploits are usually dropped and launched from these locations.
      • Endpoint hardening: Enable HVCI/Memory Integrity to make post-exploitation kernel tampering harder. Also enable LSA protection (RunAsPPL) and Credential Guard to limit LSASS dumping after escalation, and set the ASR rule "Block credential stealing from LSASS" to block mode.
      • IAM/least privilege: Remove local admin rights and rotate local admin passwords with Windows LAPS. Enforce tiering so that no domain or Tier-0 credentials are cached on Tier-2 endpoints, leaving an escalated SYSTEM process with nothing valuable to harvest.
      • Access restriction: On servers, trim "Allow log on locally" and "Allow log on through Remote Desktop Services" to the groups that actually need them. Tighten monitoring of initial-access vectors (phishing payloads, macros, stolen VPN accounts), because this bug is a typical follow-on step after initial access.

    3. Runbook step 3

      Detection rules

      • Sysmon EID 1 / Security 4688: Look for a process running as NT AUTHORITY\SYSTEM or at System integrity whose parent runs as a standard user and is not services.exe, wininit.exe or svchost.exe. KQL example: DeviceProcessEvents | where AccountSid=="S-1-5-18" and InitiatingProcessAccountSid!="S-1-5-18" and InitiatingProcessFileName !in~ ("services.exe","svchost.exe","wininit.exe")
      • EDR process ancestry: An unsigned binary in \AppData\ or \Temp\ spawns cmd.exe, powershell.exe or whoami.exe as SYSTEM shortly after launch. Treat immediate lsass.exe handle access (Sysmon EID 10, GrantedAccess 0x1010/0x1410) as a strong follow-on signal.
      • Security 4672: Special privileges (e.g. SeDebugPrivilege, SeTcbPrivilege) assigned to accounts outside admin groups. Also watch for 4720/4732 (new local account / added to Administrators) shortly after a user logon.
      • System log / WER: BugCheck event 1001 or kernel crashes referencing afd.sys on endpoints with no known networking issues. These may indicate failed exploit attempts and deserve attention when several hosts used by the same user group are affected.
      • Sigma shape: logsource: windows/process_creation, selection: IntegrityLevel: System, filter: ParentUser not in (SYSTEM, LOCAL SERVICE, NETWORK SERVICE), condition: selection and not filter. Pair it with an image-path check for user-writable directories.

    Detection rules

    No NEOSEC detection rule is available for this vulnerability yet.

    Classification under NIS2 and CRA

    Rule-based classification from exploitation status and severity. It does not replace a case-by-case assessment.

    NIS2

    NIS2 is EU Directive (EU) 2022/2555 to raise the level of cybersecurity across the Union. It substantially broadens obligations compared with the first NIS directive: more sectors, mandatory risk management, staged reporting duties and personal accountability of senior management.

    Read in glossary
    Actively exploited: treat the vulnerability as a priority in vulnerability handling under Art. 21(2)(e) NIS2. If it is exploited in your environment, check the reporting obligation under Art. 23 (early warning within 24 hours).
    CRA

    The CRA is EU Regulation (EU) 2024/2847 setting horizontal cybersecurity requirements for „products with digital elements“ — from industrial controllers and software to connected consumer devices. For the first time manufacturers must ensure security across the entire product lifecycle, handle vulnerabilities and provide security updates.

    Read in glossary
    Since 11.09.2026, manufacturers of affected products with digital elements must report actively exploited vulnerabilities under Art. 14 CRA, with an early warning within 24 hours via ENISA's single reporting platform.
    ISO/IEC 27001

    ISO/IEC 27001 is the internationally leading standard for an information security management system (ISMS). It describes a risk-based, process-oriented framework to systematically plan, implement, review and improve information security.

    Read in glossary
    Control A.8.8, management of technical vulnerabilities: assess relevance to your systems, plan remediation and keep evidence.

    Description

    Null pointer dereference in Windows Ancillary Function Driver for WinSock allows an authorized attacker to elevate privileges locally.

    Source: pwn.watch, NVD (NIST), Microsoft Security Update Guide, cvelistv5, CISA KEV Catalog, CVE.org (MITRE)

    Affected products

    The following versions are affected. Older releases of the same product line are also vulnerable unless stated otherwise.

    Affected products
    Affected versionsFixed in
    MicrosoftWindows 10 Version 1507
    • 10.0.10240.0 – < 10.0.10240.21014
    • 10.0.10240.21014
    MicrosoftWindows 10 Version 1607
    • 10.0.14393.0 – < 10.0.14393.8066
    • 10.0.14393.8066
    MicrosoftWindows 10 Version 1809
    • 10.0.17763.0 – < 10.0.17763.7314
    • 10.0.17763.7314
    MicrosoftWindows 10 Version 21H2
    • 10.0.19044.0 – < 10.0.19044.5854
    • 10.0.19044.5854
    MicrosoftWindows 10 Version 22H2
    • 10.0.19045.0 – < 10.0.19045.5854
    • 10.0.19045.5854
    MicrosoftWindows 11 version 22H2
    • 10.0.22621.0 – < 10.0.22621.5335
    • 10.0.22621.5335
    MicrosoftWindows 11 version 22H3
    • 10.0.22631.0 – < 10.0.22631.5335
    • 10.0.22631.5335
    MicrosoftWindows 11 Version 23H2
    • 10.0.22631.0 – < 10.0.22631.5335
    • 10.0.22631.5335
    MicrosoftWindows 11 Version 24H2
    • 10.0.26100.0 – < 10.0.26100.4061
    • 10.0.26100.4061
    MicrosoftWindows Server 2008 R2 Service Pack 1
    • 6.1.7601.0 – < 6.1.7601.27730
    • 6.1.7601.27730
    MicrosoftWindows Server 2008 R2 Service Pack 1 (Server Core installation)
    • 6.1.7601.0 – < 6.1.7601.27730
    • 6.1.7601.27730
    MicrosoftWindows Server 2008 Service Pack 2
    • 6.0.6003.0 – < 6.0.6003.23317
    • 6.0.6003.23317
    MicrosoftWindows Server 2008 Service Pack 2 (Server Core installation)
    • 6.0.6003.0 – < 6.0.6003.23317
    • 6.0.6003.23317
    MicrosoftWindows Server 2012
    • 6.2.9200.0 – < 6.2.9200.25475
    • 6.2.9200.25475
    MicrosoftWindows Server 2012 (Server Core installation)
    • 6.2.9200.0 – < 6.2.9200.25475
    • 6.2.9200.25475
    MicrosoftWindows Server 2012 R2
    • 6.3.9600.0 – < 6.3.9600.22577
    • 6.3.9600.22577
    MicrosoftWindows Server 2012 R2 (Server Core installation)
    • 6.3.9600.0 – < 6.3.9600.22577
    • 6.3.9600.22577
    MicrosoftWindows Server 2016
    • 10.0.14393.0 – < 10.0.14393.8066
    • 10.0.14393.8066
    MicrosoftWindows Server 2016 (Server Core installation)
    • 10.0.14393.0 – < 10.0.14393.8066
    • 10.0.14393.8066
    MicrosoftWindows Server 2019
    • 10.0.17763.0 – < 10.0.17763.7314
    • 10.0.17763.7314
    MicrosoftWindows Server 2019 (Server Core installation)
    • 10.0.17763.0 – < 10.0.17763.7314
    • 10.0.17763.7314
    MicrosoftWindows Server 2022
    • 10.0.20348.0 – < 10.0.20348.3692
    • 10.0.20348.3692
    MicrosoftWindows Server 2022, 23H2 Edition (Server Core installation)
    • 10.0.25398.0 – < 10.0.25398.1611
    • 10.0.25398.1611
    MicrosoftWindows Server 2025
    • 10.0.26100.0 – < 10.0.26100.4061
    • 10.0.26100.4061
    MicrosoftWindows Server 2025 (Server Core installation)
    • 10.0.26100.0 – < 10.0.26100.4061
    • 10.0.26100.4061

    Vendors and products

    Affected operating systems

    Affected operating systems
    Windowsmicrosoftwindows_10_1507—
    Windowsmicrosoftwindows_10_1607—
    Windowsmicrosoftwindows_10_1809—
    Windowsmicrosoftwindows_10_21h2—
    Windowsmicrosoftwindows_10_22h2—
    Windowsmicrosoftwindows_11_22h2—
    Windowsmicrosoftwindows_11_23h2—
    Windowsmicrosoftwindows_11_24h2—
    Windowsmicrosoftwindows_server_2008r2
    Windowsmicrosoftwindows_server_2008—
    Windowsmicrosoftwindows_server_2012r2
    Windowsmicrosoftwindows_server_2012—
    Windowsmicrosoftwindows_server_2016—
    Windowsmicrosoftwindows_server_2019—
    Windowsmicrosoftwindows_server_2022—
    Windowsmicrosoftwindows_server_2022_23h2—
    Windowsmicrosoftwindows_server_2025—

    Weakness classes (CWE)

    • CWE-416Use After Free

      Variant

      The product reuses or references memory after it has been freed. At some point afterward, the memory may be allocated again and saved in another pointer, while the original pointer references a location somewhere within the new allocation. Any operations using the original pointer are no longer valid because the memory "belongs" to the code that operates on the new pointer.

      Entry at MITRE CWE-416

    Public exploit references

    Publicly reported proof-of-concepts, exploit modules and detection templates for this vulnerability. NEOSEC links to the original sources only and does not provide any exploit code.

    Public exploit references
    CISA KEV CatalogCISA Known Exploited Vulnerability (opens in a new tab)cisa.govactively exploited

    References & sources

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    Badge preview for CVE-2025-32709
    <a href="https://intel.neosec.eu/en/cve/CVE-2025-32709"><img src="https://intel.neosec.eu/badge/cve/CVE-2025-32709.svg?lang=en" alt="CVE-2025-32709 – NEOSEC Intel" height="20"></a>