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 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)
CVE-2026-31788
Primary source · Revision 1
Imported from structured advisory data. Source references identify upstream records or fields; verify affected versions and your deployed configuration.
Security context
Source reference: cve:CVE-2026-31788
Linux
Source reference: /containers/cna/affected/0/product
- Affected versions
- Not stated in this record
- Fixed versions
- Not stated in this record
- Prerequisites
- Not stated in this record
Linux
Source reference: /containers/cna/affected/1/product
- Affected versions
- Not stated in this record
- Fixed versions
- Not stated in this record
- Prerequisites
- Not stated in this record
Structured affected-version data
Original package identities and version rules from this source.
[
{
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"vendor": "Linux",
"product": "Linux",
"versions": [
{
"status": "affected",
"version": "1c5de1939c204bde9cce87f4eb3d26e9f9eb732b",
"lessThan": "4eb245ff0d33b618e097a2c23de5df56d4ad6969",
"versionType": "git"
},
{
"status": "affected",
"version": "1c5de1939c204bde9cce87f4eb3d26e9f9eb732b",
"lessThan": "3ee5b9e3de4b8bdd74183d83205481c91a9effc8",
"versionType": "git"
},
{
"status": "affected",
"version": "1c5de1939c204bde9cce87f4eb3d26e9f9eb732b",
"lessThan": "87a803edb2ded911cb587c53bff179d2a2ed2a28",
"versionType": "git"
},
{
"status": "affected",
"version": "1c5de1939c204bde9cce87f4eb3d26e9f9eb732b",
"lessThan": "1879319d790f7d57622cdc22807b60ea78b56b6d",
"versionType": "git"
},
{
"status": "affected",
"version": "1c5de1939c204bde9cce87f4eb3d26e9f9eb732b",
"lessThan": "78432d8f0372c71c518096395537fa12be7ff24e",
"versionType": "git"
},
{
"status": "affected",
"version": "1c5de1939c204bde9cce87f4eb3d26e9f9eb732b",
"lessThan": "389bae9a4409934e8b8d4dbdaaf02a3ae71cf8e4",
"versionType": "git"
},
{
"status": "affected",
"version": "1c5de1939c204bde9cce87f4eb3d26e9f9eb732b",
"lessThan": "cbede2e833da1893afbea9b3ff29b5dda23a4a91",
"versionType": "git"
},
{
"status": "affected",
"version": "1c5de1939c204bde9cce87f4eb3d26e9f9eb732b",
"lessThan": "453b8fb68f3641fea970db88b7d9a153ed2a37e8",
"versionType": "git"
}
],
"programFiles": [
"drivers/xen/privcmd.c"
],
"defaultStatus": "unaffected"
},
{
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"vendor": "Linux",
"product": "Linux",
"versions": [
{
"status": "affected",
"version": "2.6.37"
},
{
"status": "unaffected",
"version": "0",
"lessThan": "2.6.37",
"versionType": "semver"
},
{
"status": "unaffected",
"version": "5.10.253",
"versionType": "semver",
"lessThanOrEqual": "5.10.*"
},
{
"status": "unaffected",
"version": "5.15.203",
"versionType": "semver",
"lessThanOrEqual": "5.15.*"
},
{
"status": "unaffected",
"version": "6.1.167",
"versionType": "semver",
"lessThanOrEqual": "6.1.*"
},
{
"status": "unaffected",
"version": "6.6.130",
"versionType": "semver",
"lessThanOrEqual": "6.6.*"
},
{
"status": "unaffected",
"version": "6.12.78",
"versionType": "semver",
"lessThanOrEqual": "6.12.*"
},
{
"status": "unaffected",
"version": "6.18.20",
"versionType": "semver",
"lessThanOrEqual": "6.18.*"
},
{
"status": "unaffected",
"version": "6.19.10",
"versionType": "semver",
"lessThanOrEqual": "6.19.*"
},
{
"status": "unaffected",
"version": "7.0",
"versionType": "original_commit_for_fix",
"lessThanOrEqual": "*"
}
],
"programFiles": [
"drivers/xen/privcmd.c"
],
"defaultStatus": "affected"
}
]- Related CVEs
- CVE-2026-31788
Source reference:
/cveMetadata/cveId
Publisher severity
high
Source reference: /containers/cna/metrics
- Event
- #39997 · Revision 1
- Added to Heist Feed
- Publisher date