Vulnerability in Xen
CVE-2026-23557
Any guest can cause xenstored to crash by issuing a XS_RESET_WATCHES command within a transaction due to an assert() triggering. In case xenstored was built with NDEBUG #defined nothing bad will happen, as assert() is doing nothing in this case. Note that the default is not to define NDEBUG for xenstored builds even in release builds of Xen.
Published · last modified .
CVSS v3 metric
CVSS v3 base score 6.5 (Medium). Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:N/I:N/A:H.
EPSS exploit prediction
EPSS: 0.002 (4.2th percentile), scored .
Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 4th percentile — 4.2% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.
EPSS over last 30 days · oldest: 0.002 · newest: 0.002 · change: 0.000
Affected products
- Xen — versions consult Xen advisory XSA-484
Weakness classification (CWE)
References
- xenbits.xenproject.org/xsa/advisory-484.html (Patch, Vendor Advisory)
- af854a3a-2127-422b-91ae-364da2661108 (Patch, Mailing List, Third Party Advisory)
- af854a3a-2127-422b-91ae-364da2661108 (Patch, Vendor Advisory)
Frequently asked questions
- What is CVE-2026-23557?
- CVE-2026-23557 is a medium-severity vulnerability in Xen, classified under Reachable Assertion. CVSS score: 6.5/10. Published 2026-05-19.
- How severe is CVE-2026-23557?
- Medium severity. CVSS v3 base score is 6.5 out of 10.