Use After Free in Linux Kernel
CVE-2021-29657
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.
Vulnerability class: TOCTOU (Time-of-Check to Time-of-Use)
EPSS: 0.004 (33.8th percentile) — read the EPSS interpretation.
CVSS v3 metric
CVSS v3 base score 7.4 (High). Vector: CVSS:3.1/AV:L/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H.
Affected products
- Linux Linux_kernel
- N/a — versions n/a
Weakness classification (CWE)
Public proof-of-concept exploits
- ARPSyndicate/cve-scores
- ARPSyndicate/cvemon
- kdn111/linux-kernel-exploitation
- khanhdn111/linux-kernel-exploitation
- khanhdz-06/linux-kernel-exploitation
- khanhdz191/linux-kernel-exploitation
- khanhhdz/linux-kernel-exploitation
- khanhhdz06/linux-kernel-exploitation
- khanhnd123/linux-kernel-exploitation
- khnhdz/linux-kernel-exploitation
References
- cve@mitre.org (VDB Entry, Third Party Advisory, x_refsource_MISC)
- cve@mitre.org (Exploit, Patch, Mailing List, Third Party Advisory, x_refsource_MISC)
- cve@mitre.org (x_refsource_CONFIRM, Patch, Third Party Advisory)
- cve@mitre.org (x_refsource_CONFIRM, Exploit, Patch, Vendor Advisory)
- cve@mitre.org (x_refsource_CONFIRM, Third Party Advisory)
Frequently asked questions
- What is CVE-2021-29657?
- CVE-2021-29657 is a high-severity vulnerability in Linux Kernel, classified under Time-of-check Time-of-use (TOCTOU) Race Condition. CVSS score: 7.4/10. Published 2021-07-22.
- How severe is CVE-2021-29657?
- High severity. CVSS v3 base score is 7.4 out of 10.
- Is CVE-2021-29657 known to be exploited?
- 16 public proof-of-concept repositories are indexed. Not currently listed in the CISA KEV catalog.