Vulnerability in Xen

[ Why it matters ]Priority signals

• Critical severity: CVSS 9.8

[ Description ]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

[ Fixes ]Fixes and patches

No fix or interim patch is linked from our sources yet. Check the vendor references below and limit exposure of affected systems until a fix is available.

[ Advisories ]Government CERT advisories

• CERT-FR14 Oct 2026CERTFR-2026-AVI-1302

  Multiple vulnerabilities in Xen Translated from French

  Multiple vulnerabilities have been discovered in Xen. Some of them allow an attacker to cause arbitrary code execution, privilege escalation and a breach of data confidentiality.

  CVE-2026-79611CVE-2023-34321CVE-2026-102700+10 more CVEs
• BSI CERT-Bund13 Oct 2026WID-SEC-2026-3930

  Xen: Multiple vulnerabilities Translated from German

  CVE-2026-102701CVE-2026-79610CVE-2026-102700+6 more CVEs

[ References ]References

• xenbits.xenproject.org/xsa/advisory-515.html
• xenbits.xen.org/xsa/advisory-515.html