Executive brief
A vulnerability in the Xen virtualization platform could allow a guest virtual machine's device model to access sensitive information from the system's memory. This occurs because the system fails to verify if enough data buffers were provided during certain operations, potentially exposing data from other virtual machines or the host system. An attacker could use this to leak confidential information, though it requires control over specific guest management components.
Technical details
A vulnerability exists in the Xen hypervisor's DM_OP (Device Model Operation) handling logic. The code assumes the caller has provided the required number of buffers for a given operation without performing explicit bounds or count checking. Consequently, certain operations may access 'stack rubble'—uninitialized data residing on the Xen kernel stack. An attacker controlling a device model (such as a de-privileged QEMU process in Dom0 or a stub domain) for an HVM guest can exploit this to leak sensitive information from the Xen stack, potentially including data belonging to other guest contexts. The issue is addressed in XSA-506 via a patch that implements proper buffer count validation.
Affected products
- Xen Project Xen 4.10 onwards
Timeline
- 2026-07-28: disclosed: Public release of XSA-506
- 2026-07-28: patched: Patch xsa506.patch released
- 2026-07-28: advisory: NVD publication date