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CVE-2016-9818 Xen CVE debrief

CVE-2016-9818 is a Xen vulnerability affecting ARM deployments in which a local guest OS user can trigger a denial of service by causing an asynchronous abort while the hypervisor is at HYP. The practical impact is a host crash, so this is primarily an availability issue for organizations running affected Xen versions on ARM systems. Vendor guidance and a patch were published alongside the vulnerability disclosure.

Vendor
Xen
Product
CVE-2016-9818
CVSS
MEDIUM 6.5
CISA KEV
Not listed in stored evidence
Original CVE published
2017-02-27
Original CVE updated
2026-05-13
Advisory published
2017-02-27
Advisory updated
2026-05-13

Who should care

System and virtualization administrators running Xen on ARM, especially those hosting untrusted or locally interactive guest workloads, should prioritize this issue because a guest-side action can crash the host.

Technical summary

NVD describes CVE-2016-9818 as a local-attack issue in Xen through 4.7.x on ARM where a guest OS user can cause a host crash via an asynchronous abort while the hypervisor is at HYP. The official record maps the issue to CVSS 3.0 AV:L/AC:L/PR:L/UI:N/S:C/C:N/I:N/A:H and CWE-284.

Defensive priority

Medium. The attack requires local guest-level access, but successful exploitation can take down the host and disrupt all workloads on it.

Recommended defensive actions

  • Apply the Xen vendor advisory and patch referenced by XSA-201.
  • Upgrade affected Xen deployments to a non-vulnerable release according to vendor guidance.
  • Review ARM hypervisor hosts that run untrusted guest workloads and prioritize patching those systems first.
  • Validate package-level vendor advisories for your Linux distribution or platform, since downstream fixes may be delivered separately.
  • Increase availability monitoring and incident response readiness for Xen hosts that cannot be patched immediately.

Evidence notes

The CVE record was published on 2017-02-27 and last modified on 2026-05-13. The supplied NVD record states that the issue affects Xen through 4.7.x on ARM and can let a local guest OS user cause a host crash via an asynchronous abort while at HYP. The reference set includes Xen advisory XSA-201, the associated patch, OSS-Security mailing list posts from 2016-11-29 and 2016-12-05, SecurityFocus BID 94581, SecurityTracker 1037358, and Gentoo GLSA-201612-56, supporting the vendor and third-party reporting timeline.

Official resources

Publicly disclosed in the CVE record on 2017-02-27, with vendor and mailing-list references in late 2016 preceding publication. The 2026-05-13 modified date reflects later record maintenance, not the original vulnerability date.