CVE-2021-29657
HIGH
7.4
CVSS Score
Published: July 22, 2021 at 04:44 PM UTC
Updated: June 17, 2026 at 03:48 AM UTC
1 product affected across 1 vendorLinux Kernel
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Severity
HIGH7.4
Exploit prediction
EPSS 0.4%
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.
Affected
Our own answer: ranges merged, affected separated from platform-only, with confidence and review flags.
5.10 ≤ v < 5.10.285.11 ≤ v < 5.11.12
Affected range stops below 5.10.28, so it looks safe — our inference, not a vendor statement
Affected range stops below 5.11.12, so it looks safe — our inference, not a vendor statement
Remediation
No guide yetNo remediation guidance has been written for this CVE yet. What the record does show:
References (5)
x_refsource_MISCThird Party AdvisoryVDB Entry
Source: [email protected]
http://packetstormsecurity.com/files/163324/KVM-nested_svm_vmrun-Double-Fetch.htmlx_refsource_MISCExploitMailing ListPatchThird Party Advisory
Source: [email protected]
https://bugs.chromium.org/p/project-zero/issues/detail?id=2177x_refsource_CONFIRMExploitPatchVendor Advisory
Source: [email protected]
https://cdn.kernel.org/pub/linux/kernel/v5.x/ChangeLog-5.11.12x_refsource_CONFIRMPatchThird Party Advisory
Source: [email protected]
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=a58d9166a756a0f4a6618e4f593232593d6df134x_refsource_CONFIRMThird Party Advisory
Source: [email protected]
https://security.netapp.com/advisory/ntap-20210902-0008/CVSS
- Attack Vector
- LOCAL
- Complexity
- HIGH
- Privileges
- NONE
- User Interaction
- NONE
- Scope
- UNCHANGED
- Confidentiality
- HIGH
- Integrity
- HIGH
- Availability
- HIGH
Vector?
Quick Info
StatusMODIFIED
CWE
CWE-367CWE-416
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