Medium [CVE-2026-72285] Reject concurrent change to CPUID entry count
This medium-severity Red Hat Linux advisory covers CVE-2026-72285 affecting Red Hat Enterprise Linux 10, Red Hat package: kernel.
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Summary
In the Linux kernel, the following vulnerability has been resolved: KVM: TDX: Reject concurrent change to CPUID entry count Reject KVM_TDX_INIT_VM if userspace changes cpuid.nent between the initial read and the subsequent copy of the initialization data. tdx_td_init() first reads user_data->cpuid.nent to size the flexible kvm_tdx_init_vm copy.
The copied structure also contains cpuid.nent, and that field can differ from the value used to size the allocation if userspace modifies the input concurrently. setup_tdparams_cpuids() later passes init_vm->cpuid.nent to kvm_find_cpuid_entry2(), which uses it as the array bound for the copied entries.
Require the copied count to match the value used to size the allocation so that CPUID parsing cannot access beyond the entries actually copied. A flaw was found in the Linux kernel's KVM (Kernel-based Virtual Machine) TDX (Trust Domain Extensions) module.
A local attacker, by concurrently modifying the CPUID entry count during the initialization of a virtual machine, could cause the CPUID parsing to access memory beyond the intended boundaries. This out-of-bounds access could potentially lead to a denial of service or other undefined behavior within the virtualized environment.
Red Hat severity: Moderate — CVSS 5.5 (CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H). Weakness: CWE-125.
Affected versions
No affected-version range was extracted from the source record. The vendor advisory is authoritative — check it before change work.
Official advisory · medium-confidence parse· fetched 24 days ago·verify at source
Fixed versions
No fixed release is recorded yet. That does not prove no patch exists — confirm against the vendor advisory.
Official advisory · medium-confidence parse· fetched 24 days ago·verify at source
Mitigation
The source record does not include mitigation steps. That is not a statement that no fix exists — read the vendor advisory below for the authoritative guidance.
Official advisory · medium-confidence parse· fetched 24 days ago·verify at source
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