CriticalCVE-2025-30400

    Microsoft DWM Core Library Elevation of Privilege Vulnerability (CVE-2025-30400)

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

    What is affected, what to do

    Use after free in Windows DWM allows an authorized attacker to elevate privileges locally.

    The vulnerability is being actively exploited; treat it as a priority. Update Microsoft Windows 10 Version 1809 to version 10.0.17763.7314, Microsoft Windows 10 Version 21H2 to version 10.0.19044.5854, Microsoft Windows 10 Version 22H2 to version 10.0.19045.5854. Immediate actions, mitigation and detection rules are in the runbook below.

    Affected
    • 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 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 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 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

    1.9 %

    EPSS score

    Moderate — model estimates 1-10% exploitation likelihood.

    Source: FIRST EPSS, percentile 79.7

    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
    198.84 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
    1.9 %
    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
    79.7
    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 local privilege escalation that needs only low privileges, no user interaction and no special conditions, and it ends in full compromise of the host. In the wild it serves as the second stage of an intrusion: after initial access via a phishing payload, stolen VPN/RDP credentials or a browser bug, attackers use it to reach SYSTEM, tamper with EDR, harvest credentials and move laterally. CISA does not flag known ransomware use, and exploitation likelihood is moderate. Even so, on session hosts, VDI and admin jump hosts in KRITIS/NIS2 environments treat this patch as critical and deploy it within days; standard clients can follow in an accelerated regular patch cycle.

    1. Runbook step 1

      Immediate response (0-24 h)

      • Deploy the Microsoft cumulative security update from May 2025 and confirm success by build number. Minimum builds: Windows 10 1809 / Server 2019 ≥ 10.0.17763.7314, Windows 10 21H2 ≥ 10.0.19044.5854, Windows 10 22H2 ≥ 10.0.19045.5854, Windows 11 22H2 ≥ 10.0.22621.5335, Windows 11 23H2 ≥ 10.0.22631.5335, Windows 11 24H2 ≥ 10.0.26100.4061. Look up the KB IDs in Microsoft's advisory for CVE-2025-30400.
      • Patch multi-user systems first: RDS/Citrix session hosts, VDI pools, jump hosts and admin workstations. On these hosts a standard user going to SYSTEM can hijack other users' sessions.
      • Identify lagging systems with Intune, MECM or WSUS compliance reports, or query (Get-ItemProperty 'HKLM:\SOFTWARE\Microsoft\Windows NT\CurrentVersion').UBR. Compare the result against the builds above.
      • Verify in the vendor advisory whether other server releases (e.g. Server 2022/2025) are affected. The supplied context does not list them.
      • Triage hosts with known initial-access events first (phishing hits, EDR alerts in the last 30 days) for signs of privilege escalation. Isolate and rotate local and cached credentials where suspicious.

    2. Runbook step 2

      Mitigation layers

      • Configuration: There is no workaround short of patching. DWM cannot be disabled on Windows 8 and later. All other controls only reduce the risk of local code execution and limit the blast radius of an escalation.
      • Application control: Enforce WDAC or AppLocker. Block execution from user-writable paths (%TEMP%, %APPDATA%, Downloads, C:\Users\Public), where exploit binaries are typically staged.
      • Endpoint hardening: Enable the ASR rules "Block executable files unless they meet a prevalence, age, or trusted list criterion" and "Block process creations originating from PSExec and WMI commands". Run EDR in block mode. Protect LSASS as PPL (RunAsPPL) and enable Credential Guard, so a SYSTEM shell does not immediately turn into credential theft.
      • IAM/least privilege: Restrict interactive and RDP logon on servers to administered groups ("Allow log on through Remote Desktop Services"). Randomise local admin passwords with Windows LAPS. Never log on with Tier-0 accounts on Tier-1/2 endpoints.
      • Network segmentation: Place jump hosts and session hosts in dedicated VLANs and block client-to-client SMB 445, WinRM 5985/5986 and RDP 3389. This keeps a local escalation from becoming domain-wide.

    3. Runbook step 3

      Detection rules

      • Unexpected children of dwm.exe (EDR / Sysmon EID 1 / Security 4688): DWM normally spawns nothing except WerFault.exe. KQL: DeviceProcessEvents | where InitiatingProcessFileName =~ "dwm.exe" and FileName !in~ ("WerFault.exe"). Sigma shape: ParentImage|endswith: '\dwm.exe' and Image not \WerFault.exe.
      • DWM crashes (Application log): Event ID 1000/1001 with faulting application dwm.exe or module dwmcore.dll may indicate failed exploit attempts. Also watch for "Desktop Window Manager" source events showing unexpected exits. Alert on clusters per host. SPL: index=wineventlog EventCode=1000 Faulting_Application="dwm.exe" | stats count by host.
      • Escalation from user context: Look for processes at IntegrityLevel=System / NT AUTHORITY\SYSTEM whose ancestry traces back to a standard user session, for example cmd.exe or powershell.exe as SYSTEM without a services.exe or Task Scheduler parent. Use the Sysmon EID 1 fields IntegrityLevel and ParentUser.
      • Suspicious image loads into dwm.exe (Sysmon EID 7): Image|endswith '\dwm.exe' with Signed: false or ImageLoaded|contains '\Users\'.
      • Post-exploitation follow-up: LSASS access (Sysmon EID 10, TargetImage lsass.exe, GrantedAccess 0x1010/0x1410), new local admins (Security 4732) and new services (System 7045) shortly after DWM anomalies on the same host.

    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

    Use after free in Windows DWM 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 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 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_1809—
    Windowsmicrosoftwindows_10_21h2—
    Windowsmicrosoftwindows_10_22h2—
    Windowsmicrosoftwindows_11_22h2—
    Windowsmicrosoftwindows_11_23h2—
    Windowsmicrosoftwindows_11_24h2—
    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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