Linux KernelOperating system · Linux
CVE-2026-31788
A fix is available.
Upgrade to 5.10.253 / 5.15.203 or later.
See remediation →
84/100
Remediation priority · High
Zero-click
Patch available
Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.
NVD · uneditedIn 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)
Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.
dbcve analysisA detailed technical summary for this CVE is being prepared.
Affected products & versions What the vendor confirmedThe version ranges the vendor confirmed as vulnerable. If your version sits inside a range here, treat yourself as exposed until you have upgraded.
NVD · CPE data
Linux KernelOperating system
Affected:
>= 2.6.37.1, < 5.10.253>= 5.11, < 5.15.203>= 5.16, < 6.1.167>= 6.2, < 6.6.130>= 6.7, < 6.12.78>= 6.13, < 6.18.20>= 6.19, < 6.19.10= 2.6.37= 7.0CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.
From the vector- Attack vector
- Local
- Complexity
- Low
- Privileges
- High
- User interaction
- None
- Scope
- Changed
- Confidentiality
- High
- Integrity
- High
- Availability
- High
CVSS:3.1/AV:L/AC:L/PR:H/UI:N/S:C/C:H/I:H/A:H
Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.
dbcve · scoped
Upgrade available
Upgrade to 5.10.253 / 5.15.203 / 6.1.167 or later
Fixed in
5.10.2535.15.2036.1.167
Vendor patch
git.kernel.org →
Recommended fix
High confidence
Upgrade to kernel >= 5.10.253, >= 5.15.203, >= 6.1.167, or >= 6.6.130 depending on your current branch
- 1. Identify the currently running kernel version using 'uname -r'
- 2. Based on your current kernel branch, upgrade to a fixed version: for 5.10.x line upgrade to >= 5.10.253, for 5.15.x upgrade to >= 5.15.203, for 6.1.x upgrade to >= 6.1.167, or for 6.6.x upgrade to >= 6.6.130
- 3. For system package managers: 'apt-get update && apt-get dist-upgrade' (Debian/Ubuntu) or 'yum update' (RHEL/CentOS) to install the newer kernel package
- 4. Reboot the system to load the patched kernel
- 5. Verify the fix is applied by checking the kernel version with 'uname -r' and confirming it meets the minimum fixed version for your branch
Caveat Kernel upgrades may require rebuilding third-party kernel modules; ensure compatible drivers are available for the new kernel version
Generated from the published advisory — verify against the referenced sources before acting.
We can perform the upgrade in your staging environment and verify nothing breaks — typical engagement from $1,950.
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References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.
Primary sourcesPractitioner notes
ContributedPeer-ranked notes from engineers who’ve handled CVE-2026-31788 in production — separate from our analysis above.
Know something about CVE-2026-31788?
The advisory tells you what broke. It rarely tells you what actually worked. If you’ve dealt with this one, that detail is what the next engineer is searching for.
- The version that genuinely resolved it — not the one the vendor claimed
- A config change or rule that shut the vector down
- A gotcha in the upgrade path that cost you an afternoon
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