Vulnerability in Xen
CVE-2026-23554
The Intel EPT paging code uses an optimization to defer flushing of any cached EPT state until the p2m lock is dropped, so that multiple modifications done under the same locked region only issue a single flush. Freeing of paging structures however is not deferred until the flushing is done, and can result in freed pages transiently being present in cached state. Such stale entries can point to memory ranges not owned by the guest, thus allowing access to unintended memory regions.
Vulnerability class: TOCTOU (Time-of-Check to Time-of-Use)
Published · last modified .
CVSS v3 metric
CVSS v3 base score 7.8 (High). Vector: CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:C/C:H/I:H/A:H.
EPSS exploit prediction
EPSS: 0.001 (2.1th percentile), scored .
Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 2nd percentile — 2.1% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.
EPSS over last 30 days · oldest: 0.001 · newest: 0.001 · change: 0.000
Affected products
- Xen — versions consult Xen advisory XSA-480
Weakness classification (CWE)
References
- xenbits.xenproject.org/xsa/advisory-480.html (Patch, Vendor Advisory)
- af854a3a-2127-422b-91ae-364da2661108 (Mailing List, Patch, Third Party Advisory)
- af854a3a-2127-422b-91ae-364da2661108 (Patch, Vendor Advisory)
Frequently asked questions
- What is CVE-2026-23554?
- CVE-2026-23554 is a high-severity vulnerability in Xen, classified under Time-of-check Time-of-use (TOCTOU) Race Condition. CVSS score: 7.8/10. Published 2026-03-23.
- How severe is CVE-2026-23554?
- High severity. CVSS v3 base score is 7.8 out of 10.