CVE-2026-23555 Xenstored DoS by unprivileged domain
An unprivileged guest can crash the Xenstore daemon or cause high CPU usage by accessing an illegal node path, impacting service availability.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Local or same network only
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-23555?
CVE-2026-23555 is a high-severity denial of service vulnerability in Xen Xen, published on 23 Mar 2026. It can only be exploited from the same machine or local network, with no action from the victim.
Official description
Any guest issuing a Xenstore command accessing a node using the (illegal) node path "/local/domain/", will crash xenstored due to a clobbered error indicator in xenstored when verifying the node path.
Note that the crash is forced via a failing assert() statement in xenstored. In case xenstored is being built with NDEBUG #defined, an unprivileged guest trying to access the node path "/local/domain/" will result in it no longer being serviced by xenstored, other guests (including dom0) will still be serviced, but xenstored will use up all cpu time it can get.
Weakness: CWE-617
Which versions are affected by CVE-2026-23555?
It affects 1 product.
Products include Xen Xen.
How do I fix CVE-2026-23555?
Apply the vendor's patch.
Upgrade, then put limits on request size, rate and nesting depth so one client cannot exhaust the service. More about Denial of service.
Is CVE-2026-23555 being exploited?
There is no known exploitation of CVE-2026-23555 in the wild and no public exploit code.
Other vulnerabilities in Xen Xen
Sources
Also known as ALPINE-CVE-2026-23555, DEBIAN-CVE-2026-23555, GHSA-hv7f-mhvh-6mf6, UBUNTU-CVE-2026-23555.