CVE-2021-29657
High
CVE-2021-29657
arch/x86/kvm/svm/nested.c in the Linux kernel before 5.11.12 has a use-after-free in which an AMD KVM guest can bypass access control on host OS MSRs when there are nested guests, aka CID-a58d9166a756. This occurs because of a TOCTOU race condition associated with a VMCB12 double fetch in nested_svm_vmrun.
Exploit probability
0.4%
Published
July 22, 2021
Required by
Not available
Last source change
April 16, 2026
02 / AFFECTED SOFTWARE
Affected packages
04 / EVIDENCE
Source records
Open Source Vulnerabilities
CVE-2021-29657
View original source
arch/x86/kvm/svm/nested.c in the Linux kernel before 5.11.12 has a use-after-free in which an AMD KVM guest can bypass access control on host OS MSRs when there are nested guests, aka CID-a58d9166a756. This occurs because of a TOCTOU race condition associated with a VMCB12 double fetch in nested_svm_vmrun.
05 / REFERENCES
Further evidence
- http://packetstormsecurity.com/files/163324/KVM-nested_svm_vmrun-Double-Fetch.html
- https://bugs.chromium.org/p/project-zero/issues/detail?id=2177
- https://cdn.kernel.org/pub/linux/kernel/v5.x/ChangeLog-5.11.12
- https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=a58d9166a756a0f4a6618e4f593232593d6df134
- https://security.netapp.com/advisory/ntap-20210902-0008/