Vulnerability · Published Sep 8, 2026 · Assigned by XEN
CVE-2026-79603Unconditionally do TLB flushing ahead of page scrubbing
Medium 4.3
In plain English
A medium-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 0.2% (higher than 13% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.
Severity (CVSS 3.1)4.3Medium
Exploit odds (30 days)0.2%top 87.1% of all CVEs
Exploited in the wildNo reportsCISA SSVC: none
Attack toolingNoneno public tooling known
Official description
x86 PV guests can free memory pages while still keeping a stale TLB entry pointing to them. A TLB flush is only issued by Xen (if needed) when the page is re-used. Since it's possible for the page to be scrubbed ahead of the TLB flush, there's a window where a PV guest can modify an already scrubbed page.
Affected packages & fixed versions
| Ecosystem | Package | Fixed in | Advisory |
|---|---|---|---|
| Alpine:v3.21 | xen | 4.19.6-r1 | ALPINE-CVE-2026-79603 |
| Alpine:v3.22 | xen | 4.20.4-r1 | ALPINE-CVE-2026-79603 |
| Alpine:v3.23 | xen | 4.20.4-r1 | ALPINE-CVE-2026-79603 |
| Alpine:v3.24 | xen | 4.21.2-r1 | ALPINE-CVE-2026-79603 |
| Debian:12 | xen | 4.17.7+13-g2445b30a44-0+deb12u1 | DEBIAN-CVE-2026-79603 |
| Debian:13 | xen | 4.20.4+39-gf1e1321c87-0+deb13u1 | DEBIAN-CVE-2026-79603 |
| Debian:14 | xen | 4.20.4+39-gf1e1321c87-1 | DEBIAN-CVE-2026-79603 |
| Ubuntu:22.04:LTS | xen | no fix listed | UBUNTU-CVE-2026-79603 |
| Ubuntu:24.04:LTS | xen | no fix listed | UBUNTU-CVE-2026-79603 |
| Ubuntu:26.04:LTS | xen | no fix listed | UBUNTU-CVE-2026-79603 |
| Ubuntu:26.10 | xen | no fix listed | UBUNTU-CVE-2026-79603 |
Affected products (as reported)
Weakness: CWE-664 · Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:N/A:N