KVM X86: Avoid stale nested state page reuse on re-VMRUN
CVE-2026-98863 Published on October 18, 2026
KVM: x86: Re-pend GET_NESTED_STATE_PAGES if getting said pages fails
In the Linux kernel, the following vulnerability has been resolved:
KVM: x86: Re-pend GET_NESTED_STATE_PAGES if getting said pages fails
Re-pend GET_NESTED_STATE_PAGES before exiting to userspace if getting the
nested pages fails in the KVM_RUN path. If userspace re-runs the vCPU, and
vmcs02 holds valid PFNs from the *previous* run of L2, then KVM could
re-enter L2 with stale, unpinned PFNs mapped into e.g. the vAPIC page.
Note, both SVM and VMX (as of commit 11722439fb20 ("KVM: nVMX: Ensure
KVM_REQ_GET_NESTED_STATE_PAGES is cleared on VM-Exit") ensure the request
is cleared on VM-Exit (including the "forced" case), i.e. there is no risk
of double-mapping due to emulated VMLAUNCH/VMRESUME/VMRUN *and* the request
trying to map the nested pages.
Products Associated with CVE-2026-98863
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Affected Versions
Linux:- Version 671ddc700fd08b94967b1e2a937020e30c838609 and below 525694a6021ec6c8f7ce1f38acdf2dd77698fec1 is affected.
- Version 671ddc700fd08b94967b1e2a937020e30c838609 and below 942192dbcd3a06695ef6b31cf10a41a21cf014d8 is affected.
- Version 671ddc700fd08b94967b1e2a937020e30c838609 and below 10180a277549339020b08000206092c07e0bff5a is affected.
- Version 5.4 is affected.
- Before 5.4 is unaffected.
- Version 6.18.56, <= 6.18.* is unaffected.
- Version 7.2.10, <= 7.2.* is unaffected.
- Version 7.3-rc5, <= * is unaffected.