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XenOperating system

CVE-2017-10918

CRITICAL · 10.0 CVSS v3.0 Published 2017-07-05
Fix available
A fix is available. Upgrade to after 4.8.1 or later.
See remediation →
100/100
Remediation priority · Urgent
Remotely reachable 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
Xen through 4.8.x does not validate memory allocations during certain P2M operations, which allows guest OS users to obtain privileged host OS access, aka XSA-222.

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

Xen hypervisor through version 4.8.x fails to validate memory allocations in certain P2M (Physical-to-Machine) address translation operations. This missing validation allows a malicious guest OS user to manipulate memory allocation paths and escalate privileges to the host OS, achieving complete host compromise.

MitigationApply the XSA-222 security patch to Xen 4.8.x or upgrade to a patched version. In high-risk environments, consider disabling HVM guest capabilities or implementing network-level access controls to limit hypervisor exposure until patching is complete.

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
XenOperating system
Affected:<= 4.8.1

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
Network
Complexity
Low
Privileges
None
User interaction
None
Scope
Changed
Confidentiality
High
Integrity
High
Availability
High

CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:C/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 `rpm -q xen` (on RHEL/CentOS) or `dpkg -l xen*` (on Debian/Ubuntu) to retrieve the installed Xen package version
    Affected if The reported version is 4.8.1 or lower, indicating the system has not been patched against XSA-222
  2. Confirm Xen hypervisor is running
    Execute `xl list` or `xm info` to verify the hypervisor is active and to display runtime version information if available
    Affected if The hypervisor is confirmed to be running an unpatched 4.8.x version
  3. Check for active HVM guest domains
    Run `xl list` and look for domains with type 'hvm' in the output, or examine the domain configuration files in /etc/xen/ for hvm=yes entries
    Affected if HVM (Hardware Virtual Machine) guests are running or configured, as the vulnerability is exploitable by malicious guest OS users
  4. Verify hypervisor boot configuration
    Inspect the GRUB configuration (typically /boot/grub/menu.lst or /boot/grub2/grub.cfg) or the Xen boot parameters visible in `xl dmesg` output to confirm the running hypervisor version matches the installed version
    Affected if The booted hypervisor matches an unpatched 4.8.x version, confirming the environment is vulnerable

A system is affected if it runs Xen 4.8.x version 4.8.1 or earlier AND has HVM guest capabilities enabled or configured, as the flaw requires a malicious guest to trigger the unsafe P2M memory allocation.

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.

dbcve · scoped
Upgrade available Upgrade to a release after 4.8.1
Interim mitigation

Apply the XSA-222 security patch to Xen 4.8.x or upgrade to a patched version. In high-risk environments, consider disabling HVM guest capabilities or implementing network-level access controls to limit hypervisor exposure until patching is complete.

Recommended fix High confidence

Xen 4.8.2 or later (recommended: Xen 4.10.x LTS or latest stable)

  1. 1. Identify the current Xen version installed on the host system using: `xm version` or `xl version`
  2. 2. Back up all virtual machine configurations and critical data before performing any upgrade
  3. 3. Plan maintenance window as all VMs will need to be shut down during the upgrade process
  4. 4. Shutdown all running virtual machines gracefully: `xl shutdown -a` or individually `xl shutdown <vm_name>`
  5. 5. Stop the Xen hypervisor and related services
  6. 6. Update package repositories and upgrade Xen packages to version 4.8.2 or later (e.g., 4.9.x, 4.10.x) using the distribution's package manager (e.g., `apt-get update && apt-get upgrade` for Debian, or `emerge --ask sys-kernel/xen` for Gentoo)
  7. 7. Verify the new Xen version is installed: `xm version` or `xl version`
  8. 8. Reboot the host system to load the new hypervisor
Caveat Upgrading Xen hypervisor requires downtime for all VMs; ensure guest VM configuration compatibility with the new Xen version before upgrading

Generated from the published advisory — verify against the referenced sources before acting.

Fix this in Xen Scoped from the published advisory
  • Consultation4.0 h
  • Implementation8.0 h
  • Testing8.0 h
  • Review / QA4.0 h
24.0 hours of engineering $4,160
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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-2017-10918 in production — separate from our analysis above.

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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