CriticalCVE-2025-22226

    VMware ESXi, Workstation, and Fusion Information Disclosure Vulnerability (CVE-2025-22226)

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

    What is affected, what to do

    VMware ESXi, Workstation, and Fusion contain an information disclosure vulnerability due to an out-of-bounds read in HGFS. A malicious actor with administrative privileges to a virtual machine may be able to exploit this issue to leak memory from the vmx process.

    The vulnerability is being actively exploited; treat it as a priority. Update VMware Workstation to version 17.6.3, VMware Fusion to version 13.6.3. Immediate actions, mitigation and detection rules are in the runbook below.

    Affected
    • ESXi gte 8.0..*
    • ESXi gte 7.0..*
    • VMware Workstation lt 17.x..17.6.3
    • VMware Fusion lt 13.x..13.6.3
    • 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
    • VMware Fusion 13.6.3

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

    Metrics

    7.1

    Priority

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

    Source: Vendor (CNA), CVSS v3

    7.1

    CVSS v3

    Severity High on the scale from 0 to 10.

    Source: SingCERT, CVE.org, pwn.watch

    1.6 %

    EPSS score

    Moderate — model estimates 1-10% exploitation likelihood.

    Source: FIRST EPSS, percentile 76.3

    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
    190.05 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
    7.1 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
    7.1
    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
    76.3
    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: partial
    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-125

    Response and mitigation

    Why act now?

    Prioritisation rationale

    On its own this is a local information leak requiring admin rights inside a guest, with moderate exploitation likelihood and no CISA ransomware flag. Its real weight comes from the scope change: leaking vmx memory gives attackers the address information needed to chain the memory-corruption bugs fixed in the same advisory into a full VM escape onto the hypervisor — which is why it made the KEV list. Treat it as top priority for hosting providers, MSPs, VDI estates and any environment where third parties hold guest admin rights; in purely internally administered estates rate it high and patch it together with the critical sibling CVEs in the next emergency maintenance window.

    1. Runbook step 1

      Immediate response (0-24 h)

      • Patch by exposure: Upgrade VMware Workstation to 17.6.3 and VMware Fusion to 13.6.3. For ESXi 7.0/8.0, VMware Cloud Foundation 4.5.x/5.x and Telco Cloud Infrastructure/Platform: patch available from the vendor — look up the fixed build numbers in the Broadcom VMware security advisory. Apply the advisory in full; it also covers VM-escape flaws (CVE-2025-22224, CVE-2025-22225).
      • Multi-tenant hosts first: Patch or vMotion-evacuate ESXi hosts where third parties (customers, contractors, developers, VDI users) hold administrator rights inside guests. The guest-to-host trust boundary matters most there.
      • Map the trust boundary: Inventory VMs whose guest admin accounts are not exclusively controlled by your own operations team. Isolate any suspected-compromised VM on an unpatched host immediately (disconnect network, snapshot for forensics, only migrate to patched hosts).
      • Disable HGFS/shared folders: Turn off shared folders globally and per VM in Workstation/Fusion until the patch is rolled out. The bug lives in the Host-Guest File System (HGFS) handling inside the vmx process.
      • Compromise check: After patching, review affected VMs' vmware.log and ESXi syslog for vmx crashes and anomalies since early March 2025 (see detection).

    2. Runbook step 2

      Mitigation layers

      • Configuration hardening (VM level): Disable the HGFS server per VM via the advanced VMX option isolation.tools.hgfsServerSet.disable = "TRUE" (per the VMware hardening guide; verify effectiveness on your version). Block shared folders in Workstation/Fusion by policy. This shrinks attack surface but does not substitute for patching the sibling CVEs.
      • IAM/least privilege in guests: Minimise local administrator/root in guest OSes (LAPS, PAM, sudo restrictions). Exploitation requires admin inside the VM — every reduction there directly lowers risk.
      • Workload separation: Place untrusted VMs (customer VMs, test boxes, malware sandboxes, VDI) on dedicated ESXi clusters; never co-host them with tier-0 systems (domain controllers, PKI, backup servers).
      • Lock down management plane: Put ESXi management (443/tcp, 902/tcp, SSH 22/tcp) and vCenter into a dedicated management VLAN reachable only via MFA-protected jump hosts. A successful escape chain typically pivots to hypervisor management next.
      • Guest endpoint hardening: Enforce kernel driver signing (Windows HVCI/vulnerable driver blocklist, Linux Secure Boot/lockdown mode) to make direct I/O access to the VMware backdoor interface harder for exploit code.

    3. Runbook step 3

      Detection rules

      • vmx process crashes (host): Search the VM's vmware.log and ESXi syslog (/var/log/vmkernel.log, /var/log/hostd.log) for "VMX panic", "Unexpected signal", or new vmx-zdump.* files in the VM directory. SPL idea: index=esxi ("vmx-zdump" OR "VMX panic" OR "Unexpected signal") | stats count by host, vm. Repeated vmx crashes on a single VM are a strong exploitation signal.
      • Linux guest — backdoor access: Exploits talk directly to the VMware backdoor (I/O port 0x5658/0x5659) and need iopl/ioperm. auditd rule: -a always,exit -F arch=b64 -S iopl -S ioperm -k vmw_backdoor — hits from anything other than open-vm-tools/vmtoolsd are highly suspicious.
      • Windows guest — drivers and tooling: Sysmon EID 6 (driver loaded) with unsigned or unknown signer, plus System event 7045 (new service, kernel driver type). KQL idea: DeviceEvents | where ActionType == "DriverLoad" and not(InitiatingProcessFileName in~ ("vmtoolsd.exe")). Also flag unusual processes interacting with vmhgfs components.
      • Follow-on host activity: New local ESXi accounts, SSH/ESXi Shell enabled, unknown VIBs (esxcli software vib list vs. baseline), shells spawned under vmx. Forward ESXi syslog to the SIEM and alert on shell/esxcli activity outside maintenance windows.
      • Network (Zeek/Suricata): Outbound connections from ESXi management IPs to the internet or guest networks are anomalous — filter Zeek conn.log for management-VLAN sources hitting destinations outside defined management targets.

    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, Workstation, and Fusion contain an information disclosure vulnerability due to an out-of-bounds read in HGFS. A malicious actor with administrative privileges to a virtual machine may be able to exploit this issue to leak memory from the vmx process.

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

    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
    —ESXi
    • ≥ 7.0
    • ≥ 8.0
    • —
    • —
    —VMware Cloud Foundation
    • 5.x, 4.5.x
    • —
    —VMware Fusion
    • 13.x – < 13.6.3
    • 13.6.3
    —VMware Telco Cloud Infrastructure
    • 3.x, 2.x
    • —
    —VMware Telco Cloud Platform
    • 5.x, 4.x, 3.x, 2.x
    • —
    —VMware Workstation
    • 17.x – < 17.6.3
    • 17.6.3
    vmwarecloud_foundation
    • —
    • —
    vmwarefusion
    • 13.0.0 – < 13.6.3
    • 13.6.3
    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-125Out-of-bounds Read

      Base

      The product reads data past the end, or before the beginning, of the intended buffer.

      Entry at MITRE CWE-125

    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, Workstation, and FusionVendor advisory, pwn-watch
    • cisa.govknown-exploited-vulnerabilities-catalog?field_cve=CVE-2025-22226government-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, Workstation, and Fusion: ESXi, Workstation, and Fusion Information Disclosure Vulnerabilitypwn-watch
    • NVD (NIST)NVD: CVE-2025-22226pwn-watch
    • cisa.govCISA Known Exploited Vulnerabilities Catalogpwn-watch
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