dbcve.org
Incorrect Default PermissionsWeakness · CWE-276

CVE-2025-27464

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

The XenBus Windows PV driver exposes a facility to userspace without a security descriptor, allowing unprivileged users full access to what should be a privileged operation. This access control vulnerability in the hypervisor paravirtualized driver enables untrusted users to interact with the XenBus interface.

MitigationApply vendor patches for the Xen PV drivers that add proper security descriptors to restrict XenBus access to privileged users only.

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. Verify Xen PV drivers are installed
    Check for Xen PV driver presence by looking for XenBus, XenNet, or Xeniface drivers in Device Manager under 'System devices' or check C:\Windows\System32\drivers\ for xen*.sys files
    Affected if No Xen PV drivers are present, the system is not vulnerable to this specific CVE
  2. Confirm XenBus driver is loaded
    Run 'sc query xenbus' or check Device Manager for 'Xen Bus' device under 'System devices' with status 'Running'
    Affected if XenBus driver is not loaded or not present, the vulnerability cannot be exploited
  3. Check XenBus device permissions
    Use 'wmic path Win32_LogicalFileSecuritySetting where "Path='C:\\Windows\\System32\\drivers\\xenbus.sys'" get' or check device security via Device Manager properties of the Xen Bus device - look for any entry granting full access to Users or Everyone
    Affected if Unprivileged users (Users group, Everyone, or non-admin accounts) have Full Control or Write access to the XenBus device or driver file
  4. Test unprivileged user access to XenBus interface
    Create a standard (non-admin) user account and attempt to access XenBus-related device objects or registry keys under HKLM\SYSTEM\CurrentControlSet\Services\XenBus
    Affected if Standard user can read/write to XenBus service configuration or device objects without elevation

The system is affected if it runs Windows with Xen PV drivers where the XenBus interface grants unprivileged users access to what should be privileged operations.

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 for the Xen PV drivers that add proper security descriptors to restrict XenBus access to privileged users only.

Have this fixed Scoped from the published advisory
  • Consultation4.0 h
  • Implementation16.0 h
  • Testing8.0 h
  • Review / QA4.0 h
32.0 hours of engineering $5,600
Get help mitigating

An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $8,960.

Scan for this in your stack

Free · runs locally
dbcve dependency scanner

Check whether your project pulls in CVE-2025-27464 — or any other known-vulnerable package — straight from your lock files. Free and open source; it runs locally and uploads nothing.

Get it on GitHub Scan in the browser

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-2025-27464 in production — separate from our analysis above.

No notes yet

Be the first to add a field note for this CVE — a mitigation you’ve verified, a version caveat, or a link to a working fix. Sign in above to contribute.

What this is

A place for practitioners to share what actually worked: a mitigation you’ve tested, a configuration change, a version- or environment-specific caveat, or a link to a verified patch. The most useful notes rise to the top as peers upvote them, so the signal stays high.

What belongs here
  • Verified mitigations, workarounds, and config changes
  • Version or environment caveats, and links to real fixes
  • No weaponised exploit code, or anything meant to cause harm
  • No spam, self-promotion, credentials, or personal data