CVE-2021-29657
Linux KVM SVM Nested Guest AMD Host MSR Access Control Bypass
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.
INFO
Published Date :
July 22, 2021, 5:15 p.m.
Last Modified :
May 19, 2023, 4:51 p.m.
Source :
[email protected]
Remotely Exploitable :
No
Impact Score :
5.9
Exploitability Score :
1.4
Public PoC/Exploit Available at Github
CVE-2021-29657 has a 2 public PoC/Exploit available at Github.
Go to the Public Exploits tab to see the list.
References to Advisories, Solutions, and Tools
Here, you will find a curated list of external links that provide in-depth
information, practical solutions, and valuable tools related to
CVE-2021-29657.
| URL | Resource |
|---|---|
| http://packetstormsecurity.com/files/163324/KVM-nested_svm_vmrun-Double-Fetch.html | Third Party Advisory VDB Entry |
| https://bugs.chromium.org/p/project-zero/issues/detail?id=2177 | Exploit Mailing List Patch Third Party Advisory |
| https://cdn.kernel.org/pub/linux/kernel/v5.x/ChangeLog-5.11.12 | Exploit Patch Vendor Advisory |
| https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=a58d9166a756a0f4a6618e4f593232593d6df134 | Patch Third Party Advisory |
| https://security.netapp.com/advisory/ntap-20210902-0008/ | Third Party Advisory |
We scan GitHub repositories to detect new proof-of-concept exploits. Following list is a collection of public exploits and proof-of-concepts, which have been published on GitHub (sorted by the most recently updated).
None
A collection of links related to Linux kernel security and exploitation
linux-kernel kernel-exploitation exploit privilege-escalation security
Results are limited to the first 15 repositories due to potential performance issues.
The following list is the news that have been mention
CVE-2021-29657 vulnerability anywhere in the article.
The following table lists the changes that have been made to the
CVE-2021-29657 vulnerability over time.
Vulnerability history details can be useful for understanding the evolution of a vulnerability, and for identifying the most recent changes that may impact the vulnerability's severity, exploitability, or other characteristics.
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CVE Modified by [email protected]
May. 14, 2024
Action Type Old Value New Value -
Reanalysis by [email protected]
May. 19, 2023
Action Type Old Value New Value Changed CPE Configuration OR *cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* versions up to (excluding) 5.11.12 OR *cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* versions from (including) 5.10 up to (excluding) 5.10.28 *cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* versions from (including) 5.11 up to (excluding) 5.11.12 -
Modified Analysis by [email protected]
Oct. 18, 2021
Action Type Old Value New Value Changed Reference Type https://security.netapp.com/advisory/ntap-20210902-0008/ No Types Assigned https://security.netapp.com/advisory/ntap-20210902-0008/ Third Party Advisory -
CVE Modified by [email protected]
Sep. 02, 2021
Action Type Old Value New Value Added Reference https://security.netapp.com/advisory/ntap-20210902-0008/ [No Types Assigned] -
Initial Analysis by [email protected]
Aug. 11, 2021
Action Type Old Value New Value Added CVSS V2 NIST (AV:L/AC:M/Au:N/C:C/I:C/A:C) Added CVSS V3.1 NIST AV:L/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H Changed Reference Type http://packetstormsecurity.com/files/163324/KVM-nested_svm_vmrun-Double-Fetch.html No Types Assigned http://packetstormsecurity.com/files/163324/KVM-nested_svm_vmrun-Double-Fetch.html Third Party Advisory, VDB Entry Changed Reference Type https://bugs.chromium.org/p/project-zero/issues/detail?id=2177 No Types Assigned https://bugs.chromium.org/p/project-zero/issues/detail?id=2177 Exploit, Mailing List, Patch, Third Party Advisory Changed Reference Type https://cdn.kernel.org/pub/linux/kernel/v5.x/ChangeLog-5.11.12 No Types Assigned https://cdn.kernel.org/pub/linux/kernel/v5.x/ChangeLog-5.11.12 Exploit, Patch, Vendor Advisory Changed Reference Type https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=a58d9166a756a0f4a6618e4f593232593d6df134 No Types Assigned https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=a58d9166a756a0f4a6618e4f593232593d6df134 Patch, Third Party Advisory Added CWE NIST CWE-367 Added CWE NIST CWE-416 Added CPE Configuration OR *cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* versions up to (excluding) 5.11.12
CWE - Common Weakness Enumeration
While CVE identifies
specific instances of vulnerabilities, CWE categorizes the common flaws or
weaknesses that can lead to vulnerabilities. CVE-2021-29657 is
associated with the following CWEs:
Common Attack Pattern Enumeration and Classification (CAPEC)
Common Attack Pattern Enumeration and Classification
(CAPEC)
stores attack patterns, which are descriptions of the common attributes and
approaches employed by adversaries to exploit the CVE-2021-29657
weaknesses.
Exploit Prediction
EPSS is a daily estimate of the probability of exploitation activity being observed over the next 30 days.
0.35 }} 0.07%
score
0.72303
percentile