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Incorrect Default PermissionsWeakness · CWE-276

CVE-2025-27462

CRITICAL · 9.4 CVSS v4.0 Published 2026-07-09
Mitigation only
No fix yet — a mitigation exists. There is no fixed release. A documented workaround reduces exposure in the meantime.
See remediation →
99/100
Remediation priority · Urgent
No privileges Zero-click 6 weeks old

Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.

NVD · unedited
[This CNA information record relates to multiple CVEs; the text explains which aspects/vulnerabilities correspond to which CVE.] The Windows PV drivers expose various facilities to userspace. Several of these have no security descriptor, and are therefore fully accessible to unprivileged users. These are: 1. XenCons, CVE-2025-27462 2. XenIface, CVE-2025-27463 3. XenBus, CVE-2025-27464

Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.

dbcve analysis · high confidence

Windows PV (paravirtualization) drivers from Xen expose kernel-level facilities to userspace without security descriptors, allowing unprivileged users full access to XenCons (CVE-2025-27462), XenIface (CVE-2025-27463), and XenBus (CVE-2025-27464). This enables local privilege escalation or potential code execution via driver IOCTLs.

MitigationApply vendor patches from Xen that add proper security descriptors to restrict driver access to privileged users only, or disable these drivers if not required.

Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.

CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.

From the vector
Attack vector
Local
Complexity
Low
Privileges
None
Authentication
X
User interaction
None
Scope
X

CVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:H/SI:H/SA:H/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X

Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.

dbcve checks

Work through these to decide whether this CVE applies to you.

  1. Identify if Xen PV drivers are installed
    Check for the presence of Xen PV driver files or services. Look for driver names including xenbus, xencons, xeniface, or check Device Manager for Xen paravirtualization devices. Run 'sc query xenbus' or check registry under HKLM\SYSTEM\CurrentControlSet\Services for Xen* keys.
    Affected if Xen PV drivers (xenbus, xencons, xeniface) are installed and running on the system
  2. Locate the Xen interface device objects
    Check for the presence of device objects in the Windows object manager. Look for device paths like \Device\XenCons, \Device\XenBus, \Device\XenIface, or check under HKLM\SYSTEM\CurrentControlSet\Services\XenCons\Parameters\Device or similar registry locations for device references.
    Affected if Xen device objects (XenCons, XenBus, XenIface) exist on the system
  3. Verify security descriptor configuration on Xen interfaces
    Query the security descriptor on the Xen device interfaces using tools like WinObj or PowerShell Get-Acl commands targeting the device namespace. Check if the SDDL (Security Descriptor Definition Language) allows access from unprivileged users (S-1-5-32-544 for Administrators, S-1-5-4 for Interactive).
    Affected if The security descriptors on Xen device interfaces grant access to unprivileged users or contain weak/null DACLs (Discretionary Access Control Lists)
  4. Test unprivileged user access to Xen interfaces
    Attempt to open or communicate with Xen device interfaces from a non-administrator account or using a low-privilege process. Monitor whether the open request succeeds or fails.
    Affected if Unprivileged (non-admin) users or processes can successfully open and communicate with XenCons, XenBus, or XenIface interfaces
  5. Check for exposed userspace facilities
    Review the Xen driver configuration and look for any user-mode DLLs or services that expose the paravirtualization interface to userspace. Check for xencons.exe, xeniface.exe, or related user-mode components that may be running or accessible.
    Affected if Userspace facilities or DLLs related to Xen PV drivers are exposed and accessible without proper access controls

The environment is affected if Xen PV drivers (xenbus, xencons, xeniface) are installed and their device interfaces lack proper security descriptors, allowing unprivileged users to access them.

Generated from the published advisory. Verify against your own configuration.

Check your environment

Paste your version and any relevant configuration and it will be compared against the affected criteria above. Do not include secrets or credentials.

AI-assisted, checked against the advisory. Informational, not a guarantee.

Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.

From vendor data
Mitigation available No clean upgrade yet — mitigate in the meantime
Mitigation

Apply vendor patches from Xen that add proper security descriptors to restrict driver access to privileged users only, or disable these drivers if not required.

Have this fixed Scoped from the published advisory
  • Consultation6.0 h
  • Implementation4.0 h
  • Testing8.0 h
  • Review / QA4.0 h
22.0 hours of engineering $3,840
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Scan for this in your stack

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References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2025-27462 in production — separate from our analysis above.

No notes yet

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What this is

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What belongs here
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  • Version or environment caveats, and links to real fixes
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