CriticalCVE-2025-22224

    VMware ESXi and Workstation TOCTOU Race Condition Vulnerability (CVE-2025-22224)

    Published In CISA KEV since Sources: CVE.org, pwn.watch, SingCERT

    What is affected, what to do

    The vulnerability CVE-2025-22224 in VMware ESXi and Workstation is a TOCTOU race condition that results in an out-of-bounds write. An attacker with local administrative privileges on a virtual machine can exploit this to execute code as the VMX process on the host. The vulnerability is actively exploited in the wild, as evidenced by its inclusion in the CISA KEV catalog. All versions of VMware ESXi and Workstation are affected. Immediate application of the latest VMware security patches is crucial to mitigate this vulnerability.

    The vulnerability is being actively exploited; treat it as a priority. Update VMware Workstation to version 17.6.3. Immediate actions, mitigation and detection rules are in the runbook below.

    Affected
    • VMware ESXi gte 8.0..*
    • VMware ESXi gte 7.0..*
    • VMware Workstation lt 17.x..17.6.3
    • VMware Cloud Foundation eq 5.x, 4.5.x..5.x, 4.5.x
    • VMware Telco Cloud Platform eq 5.x, 4.x, 3.x, 2.x..5.x, 4.x, 3.x, 2.x
    • VMware Telco Cloud Infrastructure eq 3.x, 2.x..3.x, 2.x
    Fixed in
    • VMware Workstation 17.6.3

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

    Metrics

    9.3

    Priority

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

    Source: Vendor (CNA), CVSS v3

    9.3

    CVSS v3

    Severity Critical on the scale from 0 to 10.

    Source: CVE.org, pwn.watch, SingCERT

    1.6 %

    EPSS score

    Moderate — model estimates 1-10% exploitation likelihood.

    Source: FIRST EPSS, percentile 75.2

    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
    199.81 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), CERT.at, CSA/SingCERT 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
    9.3 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
    9.3
    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
    1.6 %
    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
    75.2
    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
    CISA assessment (SSVC)
    Exploitation: active · not automatable · Technical impact: total
    Source: CISA Vulnrichment, as of 5 March 2025
    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-367

    Response and mitigation

    Why act now?

    Prioritisation rationale

    This is a VM escape: an attacker with admin rights in a guest gains code execution in the host's VMX process, breaking the core isolation guarantee of virtualisation. The vector therefore shows changed scope and full confidentiality, integrity and availability impact, despite requiring local access and high privileges. EPSS puts exploitation likelihood at a moderate level, and CISA records no known ransomware use. However, ESXi is a favoured target for actors who already hold a foothold inside a guest, and escape bugs of this kind are typically chained with other flaws. Rank it top priority for hosting, multi-tenant, VDI, sandbox and consolidated KRITIS clusters. Single-tenant estates with tightly controlled guest admins can handle it within an emergency patch window of a few days.

    1. Runbook step 1

      Immediate response (0-24 h)

      • Inventory now: Enumerate every ESXi 7.0 and 8.0 host, VMware Cloud Foundation (5.x, 4.5.x), Telco Cloud Platform (5.x–2.x), Telco Cloud Infrastructure (3.x, 2.x) and Workstation 17.x install. For example, use PowerCLI: Get-VMHost | Select Name,Version,Build. Match the builds against the Broadcom VMware security advisory.
      • Patch ESXi: A patch is available from the vendor. Look up the fixed build in the Broadcom/VMware advisory. Prioritise hosts running multi-tenant, VDI, lab or internet-facing guests. Evacuate them via vMotion first, then patch in maintenance mode.
      • Upgrade VMware Workstation to 17.6.3: Treat every 17.x release below 17.6.3 as vulnerable. Analyst and developer endpoints running untrusted guests, such as malware sandboxes, are the highest risk.
      • Handle VCF and Telco Cloud separately: Follow the product-specific advisory or the VCF async patch procedure. Do not apply standalone ESXi patches out of band to these stacks.
      • Tighten trust boundaries immediately: Until patched, keep untrusted workloads off unpatched hosts. This covers customer VMs, sandboxes and suspected-compromised servers. Move them to patched hosts or a dedicated cluster.
      • Scope existing guest compromises: Any VM where an attacker may hold admin rights is a potential escape launchpad. Bring its host into the investigation scope.

    2. Runbook step 2

      Mitigation layers

      • Workload isolation (architecture): Separate trusted and untrusted VMs onto different hosts or clusters using DRS anti-affinity or VM-host rules. Code execution in the VMX process lands at host level, so an escape affects every workload on that host.
      • Guest privilege reduction (IAM): Exploitation requires local admin inside the guest. Cut local admin accounts, enforce LAPS or PAM, and treat in-guest privilege escalation alerts as high priority. Guest hardening is the direct precondition control here.
      • Shrink the VMX attack surface (configuration): Remove unused virtual hardware and channels. This includes USB controllers, serial and parallel ports, CD/DVD drives, VMCI features, HGFS/shared folders, and copy/paste and drag-and-drop in Workstation. Follow VMware hardening guidance, e.g. isolation.tools.copy.disable = TRUE. This reduces exposure but does not replace patching.
      • Host hardening (endpoint): Enable lockdown mode and disable SSH and the ESXi Shell. Set VMkernel.Boot.execInstalledOnly and enable Secure Boot with TPM. These raise the cost of post-escape persistence.
      • Network segmentation: Keep ESXi management (vmk0) and vCenter on a dedicated management VLAN. Block outbound traffic from ESXi hosts to the internet and to user VLANs. This blocks C2 and lateral movement after an escape.
      • Workarounds: The supplied context gives no vendor-specific workaround guidance. Check the Broadcom advisory, and treat all controls above as bridging measures rather than substitutes for the patch.

    3. Runbook step 3

      Detection rules

      • VMX crashes and core dumps (ESXi logs): Forward vmware.log from VM directories, plus vmkernel.log and hostd.log, to the SIEM. Alert on unexpected VMX terminations, e.g. "VMX" AND ("PANIC" OR "core dump" OR "Unexpected signal"), and on new vmx-zdump files. Failed race attempts often crash the VMX.
      • Anomalous host processes: Hunt in ESXi shell.log and auth.log for unknown binaries, shell activity without an admin login, or processes parented by vmx. SPL example: index=esxi sourcetype=*shell* NOT user IN (known_admins).
      • Guest-side preconditions (Windows/Sysmon): Look for new kernel driver loads (Sysmon EID 6, System EID 7045) and escalation to admin or SYSTEM (Security EID 4672/4688), followed by interaction with VMware Tools or VMCI components. Sigma shape: ImageLoaded|contains: '\drivers\' combined with Signed: 'false'.
      • Network telemetry (Zeek/Suricata): Flag new outbound sessions from ESXi management IPs to external or user segments. KQL example: CommonSecurityLog | where SourceIP in (esxi_hosts) and not(ipv4_is_private(DestinationIP)).
      • Integrity drift: Watch for unauthorised VIBs (esxcli software vib list), changes to /etc/rc.local.d/local.sh, and host firewall rule modifications as persistence indicators.

    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

    VMware ESXi, and Workstation contain a TOCTOU (Time-of-Check Time-of-Use) vulnerability that leads to an out-of-bounds write. A malicious actor with local administrative privileges on a virtual machine may exploit this issue to execute code as the virtual machine's VMX process running on the host.

    Source: cvelistv5, pwn.watch, NVD (NIST), CISA KEV Catalog, CVE.org (MITRE), CSA/SingCERT

    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
    VMwareESXi
    • ≥ 8.0
    • ≥ 7.0
    • —
    • —
    VMwareTelco Cloud Infrastructure
    • 3.x, 2.x
    • —
    VMwareTelco Cloud Platform
    • 5.x, 4.x, 3.x, 2.x
    • —
    VMwareVMware Cloud Foundation
    • 5.x, 4.5.x
    • —
    VMwareWorkstation
    • 17.x – < 17.6.3
    • 17.6.3
    vmwarecloud_foundation
    • —
    • —
    vmwaretelco_cloud_infrastructure
    • 2.7
    • 2.5
    • 2.2
    • 3.0
    • —
    • —
    • —
    • —
    vmwaretelco_cloud_platform
    • 4.0.1
    • 2.5
    • 2.7
    • 4.0
    • 3.0
    • 2.0
    • 5.0
    • —
    • —
    • —
    • —
    • —
    • —
    • —
    vmwareworkstation
    • 17.0 – < 17.6.3
    • 17.6.3

    Vendors and products

    Affected operating systems

    Affected operating systems
    Othervmwareesxi7.0
    Othervmwareesxi8.0

    Weakness classes (CWE)

    • CWE-367Time-of-check Time-of-use (TOCTOU) Race Condition

      Base

      The product checks the state of a resource before using that resource, but the resource's state can change between the check and the use in a way that invalidates the results of the check.

      Entry at MITRE CWE-367

    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
    CSA/SingCERTMultiple Vulnerabilities in VMware Products (opens in a new tab)CSA/SingCERTactively exploited

    References & sources

    • support.broadcom.comVMware advisory: VMware ESXi and WorkstationVendor advisory, pwn-watch
    • cisa.govknown-exploited-vulnerabilities-catalog?field_cve=CVE-2025-22224government-resource, US government resource
    • cert.atCERT.at: Kritische Sicherheitslücken in VMware ESXi, Workstation und Fusion - aktiv ausgenutzt - Updates verfügbarcert-at
    • pwn.watchpwn.watch: VMware ESXi and Workstation: ESXi and Workstation TOCTOU Race Condition Vulnerabilitypwn-watch
    • NVD (NIST)NVD: CVE-2025-22224pwn-watch
    • cisa.govCISA Known Exploited Vulnerabilities Catalogpwn-watch
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