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.
Does this matter?
High impact if exploited, but EPSS currently rates exploitation as unlikely (0.41%). Schedule it in the normal patch cycle and watch for a rise in EPSS or a public exploit.
Description
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.
- CVSS 3.1
- 7.4 HIGHCVSS:3.1/AV:L/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H
- EPSS
- 0.41% probability · 35th percentile
- CISA KEV
- Not listed
- Weakness
- CWE-367, CWE-416
- Affected
- linux/linux kernel
- Source
- cve@mitre.org
References
- http://packetstormsecurity.com/files/163324/KVM-nested_svm_vmrun-Double-Fetch.htmlThird Party Advisory, VDB Entry
- https://bugs.chromium.org/p/project-zero/issues/detail?id=2177Exploit, Mailing List, Patch, Third Party Advisory
- https://cdn.kernel.org/pub/linux/kernel/v5.x/ChangeLog-5.11.12Exploit, Patch, Vendor Advisory
- https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=a58d9166a756a0f4a6618e4f593232593d6df134Patch, Third Party Advisory
- https://security.netapp.com/advisory/ntap-20210902-0008/Third Party Advisory
- http://packetstormsecurity.com/files/163324/KVM-nested_svm_vmrun-Double-Fetch.htmlThird Party Advisory, VDB Entry
- https://bugs.chromium.org/p/project-zero/issues/detail?id=2177Exploit, Mailing List, Patch, Third Party Advisory
- https://cdn.kernel.org/pub/linux/kernel/v5.x/ChangeLog-5.11.12Exploit, Patch, Vendor Advisory
- https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=a58d9166a756a0f4a6618e4f593232593d6df134Patch, Third Party Advisory
- https://security.netapp.com/advisory/ntap-20210902-0008/Third Party Advisory
Source: NVD record, EPSS from FIRST.org, KEV from CISA. Refreshed daily.