Xen Linux privcmd Driver privilege escalation

Summaryinfo

A vulnerability was found in Xen and classified as critical. This issue affects some unknown processing of the component Linux privcmd Driver. The manipulation results in an unknown weakness. This vulnerability was named CVE-2026-31788. There is no available exploit. A patch should be applied to remediate this issue.

Detailsinfo

A vulnerability classified as critical has been found in Xen (the affected version is unknown). Affected is an unknown code of the component Linux privcmd Driver. This is going to have an impact on confidentiality, integrity, and availability. CVE summarizes:

In the Linux kernel, the following vulnerability has been resolved: xen/privcmd: restrict usage in unprivileged domU The Xen privcmd driver allows to issue arbitrary hypercalls from user space processes. This is normally no problem, as access is usually limited to root and the hypervisor will deny any hypercalls affecting other domains. In case the guest is booted using secure boot, however, the privcmd driver would be enabling a root user process to modify e.g. kernel memory contents, thus breaking the secure boot feature. The only known case where an unprivileged domU is really needing to use the privcmd driver is the case when it is acting as the device model for another guest. In this case all hypercalls issued via the privcmd driver will target that other guest. Fortunately the privcmd driver can already be locked down to allow only hypercalls targeting a specific domain, but this mode can be activated from user land only today. The target domain can be obtained from Xenstore, so when not running in dom0 restrict the privcmd driver to that target domain from the beginning, resolving the potential problem of breaking secure boot. This is XSA-482 --- V2: - defer reading from Xenstore if Xenstore isn't ready yet (Jan Beulich) - wait in open() if target domain isn't known yet - issue message in case no target domain found (Jan Beulich)

The advisory is available at xenbits.xen.org. This vulnerability is traded as CVE-2026-31788. The exploitability is told to be easy. The technical details are unknown and an exploit is not available. The structure of the vulnerability defines a possible price range of USD $0-$5k at the moment (estimation calculated on 04/19/2026).

Applying a patch is able to eliminate this problem.

The vulnerability is also documented in the vulnerability database at EUVD (EUVD-2026-15401). If you want to get best quality of vulnerability data, you may have to visit VulDB.

Productinfo

Type

• Virtualization Software

Name

• Xen

License

• open-source

CPE 2.3info

• 🔒

CPE 2.2info

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Entryinfo

If you want to get best quality of vulnerability data, you may have to visit VulDB.

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