CVE-2016-9379: Citrix Xenserver

High severity, CVSS 7.9. EPSS: 0.4% chance of exploitation in the next 30 days.

The pygrub boot loader emulator in Xen, when S-expression output format is requested, allows local pygrub-using guest OS administrators to read or delete arbitrary files on the host via string quotes and S-expressions in the bootloader configuration file.

Affected products

• Citrix Xenserver: version 6.0.2 only; version 6.2.0 only; version 6.5 only; version 7.0 only
• Xen Xen: any version

Published 2017-01-23. Last modified 2026-06-17.