// For flags

CVE-2021-29657

KVM nested_svm_vmrun Double Fetch

Severity Score

7.4
*CVSS v3.1

Exploit Likelihood

*EPSS

Affected Versions

*CPE

Public Exploits

2
*Multiple Sources

Exploited in Wild

-
*KEV

Decision

-
*SSVC
Descriptions

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.

El archivo arch/x86/kvm/svm/nested.c en el kernel de Linux versiones anteriores a 5.11.12, presenta un uso de memoria previamente liberada en el que un invitado KVM de AMD puede omitir el control de acceso en los MSR del SO anfitrión cuando se presentan invitados anidados, también se conoce como CID-a58d9166a756. Esto ocurre debido a una condición de carrera TOCTOU asociada con un doble fetch VMCB12 en la función nested_svm_vmrun

*Credits: N/A
CVSS Scores
Attack Vector
Local
Attack Complexity
High
Privileges Required
None
User Interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High
Attack Vector
Local
Attack Complexity
Medium
Authentication
None
Confidentiality
Complete
Integrity
Complete
Availability
Complete
* Common Vulnerability Scoring System
SSVC
  • Decision:-
Exploitation
-
Automatable
-
Tech. Impact
-
* Organization's Worst-case Scenario
Timeline
  • 2021-03-31 CVE Reserved
  • 2021-05-12 CVE Published
  • 2024-08-03 CVE Updated
  • 2024-08-03 First Exploit
  • 2024-12-17 EPSS Updated
  • ---------- Exploited in Wild
  • ---------- KEV Due Date
CWE
  • CWE-367: Time-of-check Time-of-use (TOCTOU) Race Condition
  • CWE-416: Use After Free
CAPEC
Affected Vendors, Products, and Versions
Vendor Product Version Other Status
Vendor Product Version Other Status <-- --> Vendor Product Version Other Status
Linux
Search vendor "Linux"
Linux Kernel
Search vendor "Linux" for product "Linux Kernel"
>= 5.10 < 5.10.28
Search vendor "Linux" for product "Linux Kernel" and version " >= 5.10 < 5.10.28"
-
Affected
Linux
Search vendor "Linux"
Linux Kernel
Search vendor "Linux" for product "Linux Kernel"
>= 5.11 < 5.11.12
Search vendor "Linux" for product "Linux Kernel" and version " >= 5.11 < 5.11.12"
-
Affected