Vulnerability Details : CVE-2021-4093
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.
Vulnerability category: Memory Corruption
Products affected by CVE-2021-4093
- cpe:2.3:o:redhat:enterprise_linux:8.0:*:*:*:*:*:*:*
- cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*
- cpe:2.3:o:canonical:ubuntu_linux:20.04:*:*:*:lts:*:*:*
- cpe:2.3:o:canonical:ubuntu_linux:21.10:*:*:*:*:*:*:*
- cpe:2.3:o:fedoraproject:fedora:35:*:*:*:*:*:*:*
Exploit prediction scoring system (EPSS) score for CVE-2021-4093
0.04%
Probability of exploitation activity in the next 30 days
EPSS Score History
~ 7 %
Percentile, the proportion of vulnerabilities that are scored at or less
CVSS scores for CVE-2021-4093
| Base Score | Base Severity | CVSS Vector | Exploitability Score | Impact Score | Score Source | First Seen |
|---|---|---|---|---|---|---|
|
7.2
|
HIGH | AV:L/AC:L/Au:N/C:C/I:C/A:C |
3.9
|
10.0
|
NIST | |
|
8.8
|
HIGH | CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H |
2.0
|
6.0
|
NIST |
CWE ids for CVE-2021-4093
-
The product reads data past the end, or before the beginning, of the intended buffer.Assigned by:
- nvd@nist.gov (Primary)
- secalert@redhat.com (Secondary)
-
The product writes data past the end, or before the beginning, of the intended buffer.Assigned by:
- nvd@nist.gov (Primary)
- secalert@redhat.com (Secondary)
References for CVE-2021-4093
-
https://bugs.chromium.org/p/project-zero/issues/detail?id=2222
2222 - KVM: SVM: out-of-bounds read/write in sev_es_string_io - project-zeroExploit;Mailing List;Patch;Third Party Advisory
-
https://bugzilla.redhat.com/show_bug.cgi?id=2028584
2028584 – (CVE-2021-4093) CVE-2021-4093 kernel: KVM: SVM: out-of-bounds read/write in sev_es_string_ioIssue Tracking;Patch;Third Party Advisory
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