Kernel lockdown bypass in Linux Xen privcmd driver
CVE-2026-31788 is a flaw in the Linux kernel's Xen privcmd driver whereby an unprivileged Xen domU guest can use privcmd-issued hypercalls to circumvent kernel lockdown protections when the guest is booted with Secure Boot enabled. The privcmd driver permits user space processes to issue arbitrary hypercalls. While this is normally constrained by privilege and by the hypervisor's domain isolation, in a secure-booted guest this behavior allows a root process inside the guest to perform operations that undermine kernel lockdown, including modifying page tables in a way that enables user mode to modify kernel memory. The fix changes behavior for non-dom0 guests so that privcmd is restricted from the outset to hypercalls targeting only the specific backend/target domain obtained from Xenstore, rather than allowing unrestricted use until userland applies a restriction. This issue is tracked by Xen as XSA-482.
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Impact
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Mitigation
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Remediation
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Exploits
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No public exploit code observed for this vulnerability.
Affected products & vendors
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Vendor-confirmed product mapping. Mallory continuously reconciles this list against your asset inventory.
Recent activity
8 sources tracked across advisories and community write-ups. News coverage will land here when it surfaces.
No news coverage yet. Advisories and community discussion only.
The version that knows your environment.
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Every observed campaign linking this CVE to a named adversary.
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Cross-references every affected SKU, including bundled OEM variants.
Community discussion across Reddit, Mastodon, and other social sources.