CVE-2026-31788
published 2026-03-25CVE-2026-31788: In the Linux kernel, the following vulnerability has been resolved: xen/privcmd: restrict usage in unprivileged domU The Xen privcmd driver allows to issue…
PriorityP342high8.2CVSS 3.1
AVLACLPRHUINSCCHIHAH
EPSS
0.15%
5.0th percentile
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)
Affected
25 ranges
| Vendor | Product | Version range | Fixed in |
|---|---|---|---|
| debian | linux | < linux 6.19.10-1 (forky) | linux 6.19.10-1 (forky) |
| linux | linux | — | — |
| linux | linux | >= 1c5de1939c204bde9cce87f4eb3d26e9f9eb732b < 4eb245ff0d33b618e097a2c23de5df56d4ad6969 | 4eb245ff0d33b618e097a2c23de5df56d4ad6969 |
| linux | linux | >= 1c5de1939c204bde9cce87f4eb3d26e9f9eb732b < 3ee5b9e3de4b8bdd74183d83205481c91a9effc8 | 3ee5b9e3de4b8bdd74183d83205481c91a9effc8 |
| linux | linux | >= 1c5de1939c204bde9cce87f4eb3d26e9f9eb732b < 87a803edb2ded911cb587c53bff179d2a2ed2a28 | 87a803edb2ded911cb587c53bff179d2a2ed2a28 |
| linux | linux | >= 1c5de1939c204bde9cce87f4eb3d26e9f9eb732b < 1879319d790f7d57622cdc22807b60ea78b56b6d | 1879319d790f7d57622cdc22807b60ea78b56b6d |
| linux | linux | >= 1c5de1939c204bde9cce87f4eb3d26e9f9eb732b < 78432d8f0372c71c518096395537fa12be7ff24e | 78432d8f0372c71c518096395537fa12be7ff24e |
| linux | linux | >= 1c5de1939c204bde9cce87f4eb3d26e9f9eb732b < 389bae9a4409934e8b8d4dbdaaf02a3ae71cf8e4 | 389bae9a4409934e8b8d4dbdaaf02a3ae71cf8e4 |
| linux | linux | >= 1c5de1939c204bde9cce87f4eb3d26e9f9eb732b < cbede2e833da1893afbea9b3ff29b5dda23a4a91 | cbede2e833da1893afbea9b3ff29b5dda23a4a91 |
| linux | linux | >= 1c5de1939c204bde9cce87f4eb3d26e9f9eb732b < 453b8fb68f3641fea970db88b7d9a153ed2a37e8 | 453b8fb68f3641fea970db88b7d9a153ed2a37e8 |
| linux | linux_kernel | — | — |
| linux | linux_kernel | — | — |
| linux | linux_kernel | >= 0 < 6.19.10-1 | 6.19.10-1 |
| linux | linux_kernel | >= 2.6.37 < 6.1.167 | 6.1.167 |
| linux | linux_kernel | >= 2.6.37.1 < 5.10.253 | 5.10.253 |
| linux | linux_kernel | >= 5.11 < 5.15.203 | 5.15.203 |
| linux | linux_kernel | >= 5.16 < 6.1.167 | 6.1.167 |
| linux | linux_kernel | >= 6.13 < 6.18.20 | 6.18.20 |
| linux | linux_kernel | >= 6.13.0 < 6.18.20 | 6.18.20 |
| linux | linux_kernel | >= 6.19 < 6.19.10 | 6.19.10 |
| linux | linux_kernel | >= 6.19.0 < 6.19.10 | 6.19.10 |
| linux | linux_kernel | >= 6.2 < 6.6.130 | 6.6.130 |
| linux | linux_kernel | >= 6.2.0 < 6.6.130 | 6.6.130 |
| linux | linux_kernel | >= 6.7 < 6.12.78 | 6.12.78 |
| linux | linux_kernel | >= 6.7.0 < 6.12.78 | 6.12.78 |
CVSS provenance
nvdv3.18.2HIGHCVSS:3.1/AV:L/AC:L/PR:H/UI:N/S:C/C:H/I:H/A:H
osv8.2HIGH
vendor_debian8.2HIGH
vendor_redhat8.2HIGH
Stop checking back — get the weekly exploitation signal.
Every Monday: what got weaponized or added to CISA KEV in the last seven days — each CVE cross-linked to its PoC, Nuclei template, and detection rule. Free, one email a week, unsubscribe in one click.
OSV
xen/privcmd: restrict usage in unprivileged domU
osv·2026-03-25·CVSS 8.2
CVE-2026-31788 [HIGH] xen/privcmd: restrict usage in unprivileged domU
xen/privcmd: restrict usage in unprivileged domU
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 drive
GHSA
GHSA-q397-v647-xvh6: In the Linux kernel, the following vulnerability has been resolved:
xen/privcmd: restrict usage in unprivileged domU
The Xen privcmd driver allows t
ghsa_unreviewed·2026-03-25
CVE-2026-31788 [HIGH] GHSA-q397-v647-xvh6: In the Linux kernel, the following vulnerability has been resolved:
xen/privcmd: restrict usage in unprivileged domU
The Xen privcmd driver allows t
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 p
OSV
CVE-2026-31788: In the Linux kernel, the following vulnerability has been resolved: xen/privcmd: restrict usage in unprivileged domU The Xen privcmd driver allows to
osv·2026-03-25·CVSS 8.2
CVE-2026-31788 [HIGH] CVE-2026-31788: In the Linux kernel, the following vulnerability has been resolved: xen/privcmd: restrict usage in unprivileged domU The Xen privcmd driver allows to
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 privcm
Red Hat
kernel: xen/privcmd: restrict usage in unprivileged domU
vendor_redhat·2026-03-25·CVSS 8.2
CVE-2026-31788 [HIGH] CWE-266 kernel: xen/privcmd: restrict usage in unprivileged domU
kernel: xen/privcmd: restrict usage in unprivileged domU
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 d
Debian
CVE-2026-31788: linux - In the Linux kernel, the following vulnerability has been resolved: xen/privcmd...
vendor_debian·2026·CVSS 8.2
CVE-2026-31788 [HIGH] CVE-2026-31788: linux - In the Linux kernel, the following vulnerability has been resolved: xen/privcmd...
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 privcm
No detection rules found.
No public exploits indexed.
https://git.kernel.org/stable/c/1879319d790f7d57622cdc22807b60ea78b56b6dhttps://git.kernel.org/stable/c/389bae9a4409934e8b8d4dbdaaf02a3ae71cf8e4https://git.kernel.org/stable/c/3ee5b9e3de4b8bdd74183d83205481c91a9effc8https://git.kernel.org/stable/c/453b8fb68f3641fea970db88b7d9a153ed2a37e8https://git.kernel.org/stable/c/4eb245ff0d33b618e097a2c23de5df56d4ad6969https://git.kernel.org/stable/c/78432d8f0372c71c518096395537fa12be7ff24ehttps://git.kernel.org/stable/c/87a803edb2ded911cb587c53bff179d2a2ed2a28https://git.kernel.org/stable/c/cbede2e833da1893afbea9b3ff29b5dda23a4a91http://www.openwall.com/lists/oss-security/2026/03/24/2http://www.openwall.com/lists/oss-security/2026/03/24/3http://www.openwall.com/lists/oss-security/2026/03/24/4http://www.openwall.com/lists/oss-security/2026/03/24/5http://www.openwall.com/lists/oss-security/2026/03/26/4http://xenbits.xen.org/xsa/advisory-482.html
2026-03-25
Published