Vulnerability Name:

CVE-2021-4093 (CCN-220187)

Assigned:2021-09-03
Published:2021-09-03
Updated:2023-01-19
Summary: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 v3 Severity:8.8 High (CVSS v3.1 Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H)
7.7 High (Temporal CVSS v3.1 Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H/E:U/RL:O/RC:C)
Exploitability Metrics:Attack Vector (AV): Local
Attack Complexity (AC): Low
Privileges Required (PR): Low
User Interaction (UI): None
Scope:Scope (S): Changed
Impact Metrics:Confidentiality (C): High
Integrity (I): High
Availibility (A): High
6.2 Medium (CCN CVSS v3.1 Vector: CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H)
5.4 Medium (CCN Temporal CVSS v3.1 Vector: CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H/E:U/RL:O/RC:C)
Exploitability Metrics:Attack Vector (AV): Local
Attack Complexity (AC): Low
Privileges Required (PR): None
User Interaction (UI): None
Scope:Scope (S): Unchanged
Impact Metrics:Confidentiality (C): None
Integrity (I): None
Availibility (A): High
8.2 High (REDHAT CVSS v3.1 Vector: CVSS:3.1/AV:L/AC:L/PR:H/UI:N/S:C/C:H/I:H/A:H)
7.1 High (REDHAT Temporal CVSS v3.1 Vector: CVSS:3.1/AV:L/AC:L/PR:H/UI:N/S:C/C:H/I:H/A:H/E:U/RL:O/RC:C)
Exploitability Metrics:Attack Vector (AV): Local
Attack Complexity (AC): Low
Privileges Required (PR): High
User Interaction (UI): None
Scope:Scope (S): Changed
Impact Metrics:Confidentiality (C): High
Integrity (I): High
Availibility (A): High
CVSS v2 Severity:7.2 High (CVSS v2 Vector: AV:L/AC:L/Au:N/C:C/I:C/A:C)
Exploitability Metrics:Access Vector (AV): Local
Access Complexity (AC): Low
Authentication (Au): None
Impact Metrics:Confidentiality (C): Complete
Integrity (I): Complete
Availibility (A): Complete
4.9 Medium (CCN CVSS v2 Vector: AV:L/AC:L/Au:N/C:N/I:N/A:C)
Exploitability Metrics:Access Vector (AV): Local
Access Complexity (AC): Low
Athentication (Au): None
Impact Metrics:Confidentiality (C): None
Integrity (I): None
Availibility (A): Complete
Vulnerability Type:CWE-787)
Vulnerability Consequences:Denial of Service
References:Source: MITRE
Type: CNA
CVE-2021-4093

Source: CCN
Type: Google Security Research Issue 2222
KVM: SVM: out-of-bounds read/write in sev_es_string_io

Source: secalert@redhat.com
Type: Exploit, Mailing List, Patch, Third Party Advisory
secalert@redhat.com

Source: secalert@redhat.com
Type: Issue Tracking, Patch, Third Party Advisory
secalert@redhat.com

Source: XF
Type: UNKNOWN
linux-kernel-cve20214093-dos(220187)

Source: CCN
Type: Linux Kernel GIT Repository
KVM: SEV-ES: go over the sev_pio_data buffer in multiple passes if needed

Vulnerable Configuration:Configuration RedHat 1:
  • cpe:/a:redhat:enterprise_linux:8:*:*:*:*:*:*:*
    • Configuration RedHat 2:
  • cpe:/a:redhat:enterprise_linux:8::nfv:*:*:*:*:*
    • Configuration RedHat 3:
  • cpe:/a:redhat:enterprise_linux:8::realtime:*:*:*:*:*
    • Configuration RedHat 4:
  • cpe:/a:redhat:enterprise_linux:8::crb:*:*:*:*:*
    • Configuration RedHat 5:
  • cpe:/o:redhat:enterprise_linux:8:*:*:*:*:*:*:*
    • Configuration RedHat 6:
  • cpe:/o:redhat:enterprise_linux:8::baseos:*:*:*:*:*

    • Configuration CCN 1:
  • cpe:/o:linux:linux_kernel:-:*:*:*:*:*:*:*

    • * Denotes that component is vulnerable
    Oval Definitions
    Definition IDClassTitleLast Modified
    oval:com.redhat.rhsa:def:20221988
    P
    		RHSA-2022:1988: kernel security, bug fix, and enhancement update (Important)
    2022-05-10
    oval:com.redhat.rhsa:def:20221975
    P
    		RHSA-2022:1975: kernel-rt security and bug fix update (Important)
    2022-05-10
    BACK
    linux linux kernel -