CVE-2021-29657
Last modified
CVE-2021-29657 is a high-severity vulnerability rated 7.4/10 on the CVSS scale. 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.. EPSS estimates a 0.41% chance of exploitation in the next 30 days.
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.
Metrics
CVSS:3.1/AV:L/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H
Weakness Enumeration
Affected Software
| Vendor | Product | Versions |
|---|---|---|
| Linux | Linux Kernel | >= 5.10, < 5.10.28 |
| Linux | Linux Kernel | >= 5.11, < 5.11.12 |
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://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://security.netapp.com/advisory/ntap-20210902-0008/Third Party Advisory
Timeline
- Published
- Last Modified
- Status
- Modified
Frequently Asked Questions
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- How Strix found a critical auth bypass in etcdStrix autonomously discovered a critical authentication bypass in etcd, later designated CVE-2026-33413.
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