Auth bypass in Linux Kernel
CVE-2021-3653
A flaw was found in the KVM's AMD code for supporting SVM nested virtualization. The flaw occurs when processing the VMCB (virtual machine control block) provided by the L1 guest to spawn/handle a nested guest (L2). Due to improper validation of the "int_ctl" field, this issue could allow a malicious L1 to enable AVIC support (Advanced Virtual Interrupt Controller) for the L2 guest. As a result, the L2 guest would be allowed to read/write physical pages of the host, resulting in a crash of the entire system, leak of sensitive data or potential guest-to-host escape. This flaw affects Linux kernel versions prior to 5.14-rc7.
Vulnerability class: Broken Access Control
EPSS: 0.004 (36.4th percentile) — read the EPSS interpretation.
CVSS v3 metric
CVSS v3 base score 8.8 (High). Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H.
Affected products
- Linux Linux_kernel — versions 5.14
- Debian Debian_linux — versions 9.0
- Redhat Enterprise_linux — versions 7.0
- N/a Kernel — versions kernel 5.14-rc7
Weakness classification (CWE)
Public proof-of-concept exploits
References
- secalert@redhat.com (Patch, Third Party Advisory, x_refsource_MISC, Issue Tracking)
- secalert@redhat.com (Patch, Mailing List, Third Party Advisory, x_refsource_MISC)
- secalert@redhat.com (mailing-list, x_refsource_MLIST, Mailing List, Third Party Advisory)
- secalert@redhat.com (mailing-list, x_refsource_MLIST, Mailing List, Third Party Advisory)
- secalert@redhat.com (Exploit, VDB Entry, Third Party Advisory, x_refsource_MISC)
Frequently asked questions
- What is CVE-2021-3653?
- CVE-2021-3653 is a high-severity vulnerability in Linux Kernel, classified under Missing Authorization. CVSS score: 8.8/10. Published 2021-09-29.
- How severe is CVE-2021-3653?
- High severity. CVSS v3 base score is 8.8 out of 10.
- Is CVE-2021-3653 known to be exploited?
- 2 public proof-of-concept repositories are indexed. Not currently listed in the CISA KEV catalog.