CVE-2021-29657

Advisory lineage Upstream: 0 Downstream: 6
Modified
Published: 22 Jul 2021, 16:44
Last modified:03 Aug 2024, 22:11

Vulnerability Summary

Overall Risk (default)
medium
40/100
CVSS Score
7.4 HIGH
v3.1 (nvd)
EPSS Score
0.05% LOW
0% probability 0.00%
KEV
Not listed
Ransomware
No reports
Public exploits
2 found
Dark Web
Not detected

Timeline

22 Jul 2021, 16:44
Published
Vulnerability first disclosed
03 Aug 2024, 22:11
Last Modified
Vulnerability information updated

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 Metrics

  • v3.1•HIGH•Score: 7.4CVSS:3.1/AV:L/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H
  • v2.0•MEDIUM•Score: 6.9AV:L/AC:M/Au:N/C:C/I:C/A:C

EPSS Trends

Current EPSS score: 0.05%• Percentile: 15%

Techniques & Countermeasures

  • CWE-367•Time-of-check Time-of-use (TOCTOU) Race Condition

    The product checks the state of a resource before using that resource, but the resource's state can change between the check and the use in a way that invalidates the results of the check.

  • CWE-416•Use After Free

    The product reuses or references memory after it has been freed. At some point afterward, the memory may be allocated again and saved in another pointer, while the original pointer references a location somewhere within the new allocation. Any operations using the original pointer are no longer valid because the memory "belongs" to the code that operates on the new pointer.

Affected Systems

  • linux•linux_kernel

    ≥ 5.10, < 5.10.28 | ≥ 5.11, < 5.11.12

References (5)