CVE-2021-3653
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.
Does this matter?
High impact if exploited, but EPSS currently rates exploitation as unlikely (0.45%). Schedule it in the normal patch cycle and watch for a rise in EPSS or a public exploit.
Description
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.
- CVSS 3.1
- 8.8 HIGHCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H
- EPSS
- 0.45% probability · 38th percentile
- CISA KEV
- Not listed
- Weakness
- CWE-862
- Affected
- linux/linux kernel · redhat/enterprise linux · debian/debian linux
- Source
- secalert@redhat.com
References
- http://packetstormsecurity.com/files/165477/Kernel-Live-Patch-Security-Notice-LSN-0083-1.htmlExploit, Third Party Advisory, VDB Entry
- https://bugzilla.redhat.com/show_bug.cgi?id=1983686Issue Tracking, Patch, Third Party Advisory
- https://lists.debian.org/debian-lts-announce/2021/10/msg00010.htmlMailing List, Third Party Advisory
- https://lists.debian.org/debian-lts-announce/2021/12/msg00012.htmlMailing List, Third Party Advisory
- https://www.openwall.com/lists/oss-security/2021/08/16/1Mailing List, Patch, Third Party Advisory
- http://packetstormsecurity.com/files/165477/Kernel-Live-Patch-Security-Notice-LSN-0083-1.htmlExploit, Third Party Advisory, VDB Entry
- https://bugzilla.redhat.com/show_bug.cgi?id=1983686Issue Tracking, Patch, Third Party Advisory
- https://lists.debian.org/debian-lts-announce/2021/10/msg00010.htmlMailing List, Third Party Advisory
- https://lists.debian.org/debian-lts-announce/2021/12/msg00012.htmlMailing List, Third Party Advisory
- https://www.openwall.com/lists/oss-security/2021/08/16/1Mailing List, Patch, Third Party Advisory
Source: NVD record, EPSS from FIRST.org, KEV from CISA. Refreshed daily.