CVE-2015-4164: The compat_iret function in Xen 3.1 through 4.5 iterates the wrong way through a loop, which allows local 3...

Security readout for executives and security teams

This is a Xen hypervisor denial-of-service flaw. A local administrator inside a 32-bit paravirtualized guest can trigger a condition that may hang the host. The business risk is concentrated in older Xen estates and service providers where one tenant or workload can affect shared host availability. Exposure is likely limited to Xen 3.1-4.5 hosts that run 32-bit PV guests. The source bundle does not show remote unauthenticated exposure. It does show a local guest administrator prerequisite, which matters most in multi-tenant virtualization or delegated guest-admin environments. Treat this as a targeted availability risk, not an internet-wide emergency. Patch or retire affected Xen hosts, especially in shared hosting, cloud, lab, or customer-managed guest environments where guest administrators are not fully trusted. Mitigation focus: Apply updates from Xen XSA-136 and applicable vendor advisories.; Prioritize shared or tenant-facing Xen hosts running 32-bit PV guests.; Migrate unsupported Xen 3.1-4.5 systems to maintained releases..

Prepared

Jun 13, 2026, 22:39 UTC (UTC+00:00)

Generated from the cited source records. This long-tail analysis has not been individually reviewed by a named human.