CVE-2015-8338
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 · uneditedXen 4.6.x and earlier does not properly enforce limits on page order inputs for the (1) XENMEM_increase_reservation, (2) XENMEM_populate_physmap, (3) XENMEM_exchange, and possibly other HYPERVISOR_memory_op suboperations, which allows ARM guest OS administrators to cause a denial of service (CPU consumption, guest reboot, or watchdog timeout and host reboot) and possibly have unspecified other impact via unknown vectors.
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 confidenceXen 4.6.x and earlier fails to properly validate/enforce limits on page order inputs in memory management hypercalls (XENMEM_increase_reservation, XENMEM_populate_physmap, XENMEM_exchange), allowing malicious ARM guest administrators to manipulate page order values causing host CPU exhaustion, guest or host crashes, and watchdog-triggered reboots.
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<= 4.6.0CVSS 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
- Authentication
- None
- Confidentiality
- Complete
- Integrity
- Complete
- Availability
- Complete
AV:L/AC:L/Au:N/C:C/I:C/A:C
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 checksWork through these to decide whether this CVE applies to you.
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Identify installed Xen versionRun 'xl version' or 'xm version' to display the Xen hypervisor version, or use 'rpm -q xen' on RHEL-based systemsAffected if Version is 4.6.0 or earlier (any 4.6.x, 4.5.x, 4.4.x, etc.)
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Confirm hypervisor architectureCheck the output of 'xl info' or 'xm info' for the 'xen_version' string or verify architecture via 'uname -a' with Xen kernelAffected if The hypervisor is built for ARM architecture (the vulnerability only affects ARM guests)
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List running ARM-based guest domainsRun 'xl list' to see all running VMs, then check each guest's configuration with 'xl config-list <domain>' or examine /etc/xen/<domain> for arch typeAffected if ARM-based guest domains are running on an affected Xen version
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Verify vulnerable hypercall accessibilityReview /sys/hypervisor/permissions or check xen-accessible hypercalls via 'xl dmseg' logs for memory management hypercall activity from guestsAffected if Guests have access to XENMEM_increase_reservation, XENMEM_populate_physmap, or XENMEM_exchange hypercalls (default for paravirtualized guests)
You are affected if Xen version is 4.6.0 or earlier AND ARM guest domains with access to memory management hypercalls are running.
Generated from the published advisory. Verify against your own configuration.
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 dataUpgrade Xen to version 4.6.1 or later which implements proper page order input validation; for immediate mitigation, restrict or monitor ARM guest hypercall access and consider disabling vulnerable memory operations if not required.
- Consultation8.0 h
- Implementation12.0 h
- Testing8.0 h
- Review / QA4.0 h
An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $9,088.
Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2015-8338 — or any other known-vulnerable package — straight from your lock files. Free and open source; it runs locally and uploads nothing.
References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.
Primary sourcesPractitioner notes
ContributedPeer-ranked notes from engineers who’ve handled CVE-2015-8338 in production — separate from our analysis above.
The advisory tells you what broke. It rarely tells you what actually worked. If you’ve dealt with this one, that detail is what the next engineer is searching for.
- The version that genuinely resolved it — not the one the vendor claimed
- A config change or rule that shut the vector down
- A gotcha in the upgrade path that cost you an afternoon
No notes yet
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- Verified mitigations, workarounds, and config changes
- Version or environment caveats, and links to real fixes
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