Incorrect Privilege Assignment Affecting kernel-modules-extra-matched package, versions *


Severity

Recommended
0.0
medium
0
10

Based on CentOS security rating.

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  • Snyk IDSNYK-CENTOS10-KERNELMODULESEXTRAMATCHED-15774871
  • published26 Mar 2026
  • disclosed25 Mar 2026

Introduced: 25 Mar 2026

NewCVE-2026-31788  (opens in a new tab)
CWE-266  (opens in a new tab)

How to fix?

There is no fixed version for Centos:10 kernel-modules-extra-matched.

NVD Description

Note: Versions mentioned in the description apply only to the upstream kernel-modules-extra-matched package and not the kernel-modules-extra-matched package as distributed by Centos. See How to fix? for Centos:10 relevant fixed versions and status.

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)

CVSS Base Scores

version 3.1