CVE-2026-23557
Xenstored Assertion Failure in Transaction Handling
Publication date: 2026-05-19
Last updated on: 2026-05-19
Assigner: Xen Project
Description
Description
CVSS Scores
EPSS Scores
| Probability: | |
| Percentile: |
Meta Information
Affected Vendors & Products
| Vendor | Product | Version / Range |
|---|---|---|
| xen | xen | From 4.2.0 (inc) |
Helpful Resources
Exploitability
| CWE ID | Description |
|---|---|
| CWE-617 | The product contains an assert() or similar statement that can be triggered by an attacker, which leads to an application exit or other behavior that is more severe than necessary. |
Attack-Flow Graph
AI Powered Q&A
How does this vulnerability affect compliance with common standards and regulations (like GDPR, HIPAA)?:
The provided information does not specify any direct impact of this vulnerability on compliance with common standards and regulations such as GDPR or HIPAA.
How can this vulnerability be detected on my network or system? Can you suggest some commands?
There is no specific detection method or commands provided in the available resources to identify exploitation of this vulnerability on your network or system.
The vulnerability involves any unprivileged guest domain sending an XS_RESET_WATCHES command within a transaction to xenstored, causing it to crash due to an assert() failure. Monitoring for unexpected crashes or restarts of the xenstored service could be an indirect indicator.
Since no explicit detection commands or network signatures are documented, the best approach is to ensure your Xen system is patched to the fixed versions.
Can you explain this vulnerability to me?
CVE-2026-23557 is a vulnerability in Xen's xenstored service where any guest can cause the service to crash by issuing an XS_RESET_WATCHES command within a transaction.
The crash happens because an assert() statement is triggered, which causes xenstored to terminate unexpectedly.
This vulnerability affects systems where xenstored is built without the NDEBUG macro defined, which is the default for most Xen releases.
Systems using the OCaml variant (oxenstored) or the C variant built with NDEBUG defined are not vulnerable.
The issue impacts all Xen systems from version 4.2 onwards, while versions prior to 4.1 are unaffected.
How can this vulnerability impact me? :
This vulnerability can cause a denial of service (DoS) by crashing the xenstored service.
When xenstored crashes, further Xenstore operations become impossible, which affects domain administration and management.
This means that any guest can disrupt the normal operation of the Xen environment by triggering this crash.
There is no known mitigation other than applying patches that fix the issue.
What immediate steps should I take to mitigate this vulnerability?
There is no known mitigation to prevent this vulnerability from being exploited without applying patches.
The recommended immediate step is to apply the available patches for the affected Xen versions to resolve the issue.
Note that the vulnerability only affects xenstored built without NDEBUG defined, which is the default for most Xen releases.