CVE-2021-4093
A KVM guest using SEV-ES can trigger out-of-bounds reads and writes in the host kernel via a malicious VMGEXIT for a string I/O instruction (for example, outs or ins) using the exit reason SVM_EXIT_IOIO.
Does this matter?
High impact if exploited, but EPSS currently rates exploitation as unlikely (0.42%). 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 the Secure Encrypted Virtualization-Encrypted State (SEV-ES). A KVM guest using SEV-ES can trigger out-of-bounds reads and writes in the host kernel via a malicious VMGEXIT for a string I/O instruction (for example, outs or ins) using the exit reason SVM_EXIT_IOIO. This issue results in a crash of the entire system or a potential guest-to-host escape scenario.
- 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
- 0.42% probability · 35th percentile
- CISA KEV
- Not listed
- Weakness
- CWE-125, CWE-787
- Affected
- linux/linux kernel · redhat/enterprise linux · fedoraproject/fedora · canonical/ubuntu linux
- Source
- secalert@redhat.com
References
- https://bugs.chromium.org/p/project-zero/issues/detail?id=2222Exploit, Mailing List, Patch, Third Party Advisory
- https://bugzilla.redhat.com/show_bug.cgi?id=2028584Issue Tracking, Patch, Third Party Advisory
- https://bugs.chromium.org/p/project-zero/issues/detail?id=2222Exploit, Mailing List, Patch, Third Party Advisory
- https://bugzilla.redhat.com/show_bug.cgi?id=2028584Issue Tracking, Patch, Third Party Advisory
Source: NVD record, EPSS from FIRST.org, KEV from CISA. Refreshed daily.