Vulnerability · Published Jul 9, 2026 · Assigned by XEN
CVE-2026-23556oxenstored keeps quota related use counts across domain destruction
Critical 9.4
In plain English
A critical-severity security flaw in oxenstored 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.
Severity (CVSS 4.0)9.4Critical
Exploit odds (30 days)0.1%top 96.9% of all CVEs
Exploited in the wildNo reportsCISA SSVC: none
Attack toolingNoneno public tooling known
Official description
When oxenstored is tearing a domain down, the node data is cleaned up but the usage counts are leaked. When the domain ID is eventually reused, the new domain can create fewer nodes before beeing deemed to be over quota.
Affected packages & fixed versions
| Ecosystem | Package | Fixed in | Advisory |
|---|---|---|---|
| Alpine:v3.20 | xen | 0 | ALPINE-CVE-2026-23556 |
| Alpine:v3.21 | xen | 0 | ALPINE-CVE-2026-23556 |
| Alpine:v3.22 | xen | 0 | ALPINE-CVE-2026-23556 |
| Alpine:v3.23 | xen | 0 | ALPINE-CVE-2026-23556 |
| Alpine:v3.24 | xen | 0 | ALPINE-CVE-2026-23556 |
| Debian:12 | xen | 4.17.7-0+deb12u1 | DEBIAN-CVE-2026-23556 |
| Debian:13 | xen | 4.20.3+127-gc42374a105-0+deb13u1 | DEBIAN-CVE-2026-23556 |
| Debian:14 | xen | 4.20.3+127-gc42374a105-1 | DEBIAN-CVE-2026-23556 |
| Ubuntu:22.04:LTS | xen | no fix listed | UBUNTU-CVE-2026-23556 |
| Ubuntu:24.04:LTS | xen | no fix listed | UBUNTU-CVE-2026-23556 |
| Ubuntu:25.10 | xen | no fix listed | UBUNTU-CVE-2026-23556 |
| Ubuntu:26.04:LTS | xen | no fix listed | UBUNTU-CVE-2026-23556 |
| Ubuntu:26.10 | xen | no fix listed | UBUNTU-CVE-2026-23556 |
Affected products (as reported)
| Vendor | Product | Versions |
|---|---|---|
| Xen | oxenstored | all |
Weakness: CWE-281 · Vector: CVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:H/SI:H/SA:H