Vulnerability · Published Mar 23, 2026 · Assigned by XEN
CVE-2026-23554Use after free of paging structures in EPT
High 7.8
In plain English
A high-severity security flaw in Xen from Xen. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.1% (higher than 3% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.
Official description
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.
Affected packages & fixed versions
| Ecosystem | Package | Fixed in | Advisory |
|---|---|---|---|
| Alpine:v3.20 | xen | 4.18.5-r5 | ALPINE-CVE-2026-23554 |
| Alpine:v3.21 | xen | 4.19.4-r2 | ALPINE-CVE-2026-23554 |
| Alpine:v3.22 | xen | 4.20.2-r2 | ALPINE-CVE-2026-23554 |
| Alpine:v3.23 | xen | 4.20.2-r2 | ALPINE-CVE-2026-23554 |
| Alpine:v3.24 | xen | 4.21.0-r3 | ALPINE-CVE-2026-23554 |
| Debian:12 | xen | 4.17.7-0+deb12u1 | DEBIAN-CVE-2026-23554 |
| Debian:13 | xen | 4.20.3+127-gc42374a105-0+deb13u1 | DEBIAN-CVE-2026-23554 |
| Debian:14 | xen | 4.20.3+127-gc42374a105-1 | DEBIAN-CVE-2026-23554 |
| Ubuntu:22.04:LTS | xen | no fix listed | UBUNTU-CVE-2026-23554 |
| Ubuntu:24.04:LTS | xen | no fix listed | UBUNTU-CVE-2026-23554 |
| Ubuntu:25.10 | xen | no fix listed | UBUNTU-CVE-2026-23554 |
| Ubuntu:26.04:LTS | xen | no fix listed | UBUNTU-CVE-2026-23554 |
| Ubuntu:26.10 | xen | no fix listed | UBUNTU-CVE-2026-23554 |
Affected products (as reported)
Weakness: CWE-367 · Vector: CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:C/C:H/I:H/A:H