Race condition in Xen - CVE-2026-62436
Published: July 29, 2026
Vulnerability identifier: #VU140024
CSH Severity: Low
CVSS v4: 7.3 [CVSS:4.0/AV:L/AC:L/AT:P/PR:L/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N]
CVE-ID: CVE-2026-62436
CWE-ID: CWE-362
Exploitation vector: Local access
Exploit availability:
No public exploit available
Vulnerability details
The vulnerability allows a local user to escalate privileges.
The vulnerability exists due to a race condition in grant-table version switching logic when switching from grant table v2 to v1 while other grant-table operations are in progress. A local user can trigger concurrent grant-table operations in a multi-vCPU guest to escalate privileges.
Only x86 guests permitted to use grant table version 2 interfaces are vulnerable, and exploitation requires a multi-vCPU guest.
Affected software
Xen
Debian Linux
Fedora
Citrix XenServer
xen (Debian package)
xen
Debian Linux
Fedora
Citrix XenServer
xen (Debian package)
xen
How to mitigate CVE-2026-62436
Install security update from vendor's website.
xen (Debian package) - update to 4.20.3+127-gc42374a105-0+deb13u1
xen - addressed in versions 4.20.4-1.fc43, 4.21.2-1.fc44
xen - addressed in versions 4.20.4-1.fc43, 4.21.2-1.fc44