CVE-2015-8615
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 · uneditedThe hvm_set_callback_via function in arch/x86/hvm/irq.c in Xen 4.6 does not limit the number of printk console messages when logging the new callback method, which allows local HVM guest OS users to cause a denial of service via a large number of changes to the callback method (HVM_PARAM_CALLBACK_IRQ).
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 confidenceThe hvm_set_callback_via function in Xen 4.6 hypervisor lacks rate limiting on printk console messages when logging callback method changes via HVM_PARAM_CALLBACK_IRQ. Local HVM guest users can repeatedly trigger callback changes to flood the host's console, causing denial of service.
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
- Network
- Complexity
- Low
- Privileges
- Low
- User interaction
- None
- Scope
- Changed
- Confidentiality
- None
- Integrity
- None
- Availability
- Low
CVSS:3.0/AV:N/AC:L/PR:L/UI:N/S:C/C:N/I:N/A:L
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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Check the Xen hypervisor versionRun `xl info` or `xm info` and look for the 'xen_version' field, or check the installed package version with `rpm -q xen` or `dpkg -l xen*` depending on your Linux distributionAffected if The version shows exactly 4.6.0 - versions 4.6.1 and later are not affected
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Identify running HVM guestsRun `xl list` or `xl list -l` and examine the 'HVM' column or 'builder' field for each guest domainAffected if Any guest is listed as type HVM (Hardware Virtual Machine) - the vulnerability only affects HVM guests, not paravirtualized (PV) guests
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Check if HVM callback IRQ parameter is in useFor each HVM guest, query the hypervisor with `xl debug-keys u` followed by `xl dmesg` to look for HVM_PARAM_CALLBACK_IRQ messages, or check guest config files in /etc/xen/ for 'callback_irq' settingsAffected if Console logs show repeated callback method change messages via HVM_PARAM_CALLBACK_IRQ, indicating the vulnerable code path is being exercised
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Monitor console for rate-limited message floodObserve the domain 0 console (xm dmesg or xl dmesg) while triggering callback changes in an HVM guest - repeatedly attach/detach devices or change configuration to trigger HVM_PARAM_CALLBACK_IRQ modificationsAffected if The console output shows rapid, repetitive logging of callback changes without any rate limiting or throttling between messages
A system is affected if it runs Xen version 4.6.0 with any HVM guests that utilize the HVM_PARAM_CALLBACK_IRQ parameter, as this enables the unbounded console flood attack vector.
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 dataApply the upstream patch that adds rate limiting to the printk calls in hvm_set_callback_via, or upgrade to Xen 4.6.1 or later where this issue is resolved. Consider disabling verbose callback logging in production environments.
- Consultation3.0 h
- Implementation4.0 h
- Testing6.0 h
- Review / QA2.0 h
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Free · runs locallyCheck whether your project pulls in CVE-2015-8615 — 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-2015-8615 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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- Version or environment caveats, and links to real fixes
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