CVE-2026-23555: Any guest issuing a Xenstore command accessing a node using the (illegal) node path "/local/domain/", will cra

Routine

HIGH 7.1MITIGATE

CVE-2026-23555 is a high-severity flaw (CVSS 7.1) affecting xen. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

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

Why this priority

High severity

No fix is published yet: follow the downgrade or mitigation steps.

Risk facts

CVSS score	7.1 (High)
Attack vector	Local
Attack complexity	Low
Privileges needed	None
User interaction	None
EPSS exploit chance	0.2% (top 92%)
CISA exploited list	No
Weakness	CWE-617
Published	2026-03-23
Last modified	2026-06-17

Publisher (CNA): Xen Project · Vendor: xen

Last updated 2026-06-17 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2026-03-23 07:16 UTCPublished CVE record published
2026-06-17 10:21 UTCUpdated Record last modified

xen xen MITIGATE

Affected: >= 4.18.0

Fixed in: no fixed release known

Safe to downgrade to: a release before 4.18.0

Check your OS release

cat /etc/os-release; uname -r

Debian / Ubuntu

sudo apt update && sudo apt full-upgrade

RHEL / Amazon Linux / Fedora

sudo dnf upgrade --refresh

Windows

Install the latest cumulative update from Windows Update

If no patch exists yet

OS downgrades are not safe. Apply the vendor mitigation from the advisory and restrict exposure.

Verify at the official source NVD · CVE Program · Report a problem with this page
Scores and fixes here are computed automatically from those and other public sources. Confirm with the vendor advisory before changing production systems.

Quick answers

How do I fix CVE-2026-23555?

xen: mitigate or apply the listed mitigation. Exact commands for each OS are on this page.

Is CVE-2026-23555 being exploited?

CVE-2026-23555 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

What does CVE-2026-23555 affect?

CVE-2026-23555 affects xen. Severity is high (CVSS 7.1). 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 fa

How urgent is CVE-2026-23555?

Priority 27/100. High severity

Software pages

Xen vulnerabilities

Related CVEs

CVE-2026-23558 HIGH 7.8 MITIGATE The adjustments made for XSA-379 as well as those subsequently becoming XSA-387 still left a race window, when
CVE-2026-23557 MEDIUM 6.5 MITIGATE Any guest can cause xenstored to crash by issuing a XS_RESET_WATCHES command within a transaction due to an as
CVE-2026-23554 HIGH 7.8 MITIGATE The Intel EPT paging code uses an optimization to defer flushing of any cached EPT state until the p2m lock is
CVE-2026-23553 LOW 2.9 MITIGATE In the context switch logic Xen attempts to skip an IBPB in the case of a vCPU returning to a CPU on which it
CVE-2025-58150 HIGH 8.8 MITIGATE Shadow mode tracing code uses a set of per-CPU variables to avoid cumbersome parameter passing

References

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