Vulnerability · Published Oct 13, 2026 · Assigned by XEN
CVE-2026-79608x86/AMD: ineffectual Zenbleed workaround
Critical 9.8
In plain English
A critical-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 0.3% (higher than 27% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.
Official description
The workaround for XSA-433 (Zenbleed, CVE-2023-20593) was later re-worked to better integrate with other manipulations of the same MSR. In this rework an inverted conditional was introduced, resulting in the workaround to not be applied when needed and vice versa. For more details, see: http://xenbits.xen.org/xsa/advisory-433.html
Affected packages & fixed versions
| Ecosystem | Package | Fixed in | Advisory |
|---|---|---|---|
| Alpine:v3.21 | xen | 4.19.6-r2 | ALPINE-CVE-2026-79608 |
| Alpine:v3.22 | xen | 4.20.4-r2 | ALPINE-CVE-2026-79608 |
| Alpine:v3.23 | xen | 4.20.4-r2 | ALPINE-CVE-2026-79608 |
| Alpine:v3.24 | xen | 4.21.2-r2 | ALPINE-CVE-2026-79608 |
| Debian:13 | xen | 4.20.4+39-gf1e1321c87-0+deb13u1 | DEBIAN-CVE-2026-79608 |
| Debian:14 | xen | 4.20.4+39-gf1e1321c87-1 | DEBIAN-CVE-2026-79608 |
| Ubuntu:22.04:LTS | xen | no fix listed | UBUNTU-CVE-2026-79608 |
| Ubuntu:24.04:LTS | xen | no fix listed | UBUNTU-CVE-2026-79608 |
| Ubuntu:26.04:LTS | xen | no fix listed | UBUNTU-CVE-2026-79608 |
| Ubuntu:26.10 | xen | no fix listed | UBUNTU-CVE-2026-79608 |
Affected products (as reported)
Weakness: CWE-670 · Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H