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Vm ServerOperating system · Oracle

CVE-2016-4480

HIGH · 8.4 CVSS v3.0 Published 2016-05-18
Fix available
A fix is available. Upgrade to after 4.6.1 or later.
See remediation →
89/100
Remediation priority · High
No privileges Zero-click

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
The guest_walk_tables function in arch/x86/mm/guest_walk.c in Xen 4.6.x and earlier does not properly handle the Page Size (PS) page table entry bit at the L4 and L3 page table levels, which might allow local guest OS users to gain privileges via a crafted mapping of memory.

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 guest_walk_tables function in Xen 4.6.x and earlier fails to properly validate the Page Size (PS) bit in page table entries at the L4 and L3 levels. This allows a local guest OS user to potentially manipulate memory mappings to escalate privileges within the guest context.

MitigationApply Xen security patch (4.6.1 or later). If immediate patching is not feasible, restrict or monitor untrusted guest VM access and consider virtualization-based security isolation.

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

Affected products & versions What the vendor confirmedThe version ranges the vendor confirmed as vulnerable. If your version sits inside a range here, treat yourself as exposed until you have upgraded.

NVD · CPE data
Vm ServerOperating system
Affected:= 3.2= 3.3= 3.4
XenOperating system
Affected:<= 4.6.1

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
User interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High

CVSS:3.0/AV:L/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

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 installed Xen hypervisor version
    Run 'xl version' or 'xm version' or check '/usr/lib/xen/bin/xen-version' to determine the Xen version running on the host
    Affected if The version is 4.6.1 or earlier (e.g., 4.6.0, 4.5.x, 4.4.x, etc.)
  2. Identify Oracle VM Server version
    Check /etc/oracle-release, /etc/vm-server-version, or run 'ovs-agent --version' to determine Oracle VM Server version
    Affected if The version is 3.2, 3.3, or 3.4 (these are based on Xen 4.6.x and earlier)
  3. Confirm hypervisor is exposed to untrusted guests
    List running virtual machines with 'xl list' or 'xm list' and identify whether any guests are untrusted or multi-tenant
    Affected if Untrusted or potentially malicious guest VMs are running on the hypervisor, as exploitation requires a local guest OS user to manipulate page tables

You are affected if your hypervisor runs Xen 4.6.1 or earlier (or Oracle VM Server 3.2/3.3/3.4) AND hosts untrusted guest VMs that could exploit the PS bit validation flaw to escalate privileges within the guest context.

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
Upgrade available Upgrade to a release after 4.6.1
Interim mitigation

Apply Xen security patch (4.6.1 or later). If immediate patching is not feasible, restrict or monitor untrusted guest VM access and consider virtualization-based security isolation.

Fix this in Vm Server Scoped from the published advisory
  • Consultation2.0 h
  • Implementation4.0 h
  • Testing4.0 h
  • Review / QA2.0 h
12.0 hours of engineering $2,080
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An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $3,328.

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-2016-4480 in production — separate from our analysis above.

No notes yet

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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