Bug 2481944 (CVE-2026-46059)

Summary: CVE-2026-46059 kernel: KVM: nSVM: Always use NextRIP as vmcb02's NextRIP after first L2 VMRUN
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security <prodsec-ir-bot>
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Version: unspecifiedCC: rhel-process-autobot, watson-tool-maintainers
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OS: Linux   
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A flaw was found in the Linux kernel's KVM (Kernel-based Virtual Machine) nSVM module. This vulnerability occurs when running nested virtual machines (L2 guests) with NRIPS (Next Instruction Pointer Suppression) disabled. After an L2 guest's initial run, the `NextRIP` value in `vmcb02` may not be correctly updated, potentially leading to incorrect program execution flow within the virtualized environment. This issue could affect the stability or integrity of the guest system.
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Description OSIDB Bzimport 2026-05-27 15:03:36 UTC 
In the Linux kernel, the following vulnerability has been resolved:

KVM: nSVM: Always use NextRIP as vmcb02's NextRIP after first L2 VMRUN

For guests with NRIPS disabled, L1 does not provide NextRIP when running
an L2 with an injected soft interrupt, instead it advances the current RIP
before running it. KVM uses the current RIP as the NextRIP in vmcb02 to
emulate a CPU without NRIPS.

However, after L2 runs the first time, NextRIP will be updated by the CPU
and/or KVM, and the current RIP is no longer the correct value to use in
vmcb02.  Hence, after save/restore, use the current RIP if and only if a
nested run is pending, otherwise use NextRIP.  Give soft_int_next_rip the
same treatment, as it's the same logic, just for a narrower use case.

[sean: give soft_int_next_rip the same treatment]
Comment 1 Keith Grant 2026-05-27 18:50:40 UTC 
Upstream advisory:
https://lore.kernel.org/linux-cve-announce/2026052755-CVE-2026-46059-6ef4@gregkh/T