CVE intelligence and bounded remediation

CVE-2021-4093 — A flaw was found in the KVM's AMD code for supporting the Secure Encrypted Virtualization-Encrypted State (SEV-ES)

High CVSS 8.8

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.

Severity
High
CVSS
8.8 (3.1)
Published
2022-02-18
CISA KEV
Not currently listed
Ecosystem
linux/kernel
Weaknesses
CWE-125, CWE-787

Affected products

  • linux / linux_kernel
  • redhat / enterprise_linux / 8.0
  • fedoraproject / fedora / 35
  • canonical / ubuntu_linux / 20.04
  • canonical / ubuntu_linux / 21.10

Matched remediation archetype

Buffer bounds, memory safety, and memory corruption

This catalog composition supplies bounded fallback guidance. Explicitly reviewed curated workflows load with the complete record below.

Check exposure

  • Identify affected native-code versions, build flags, architectures, parsers, codecs, drivers, and input paths in all shipped artifacts.
  • Determine whether untrusted data reaches the affected routine and the process privilege, sandbox, and network exposure.
  • Confirm statically linked, vendored, firmware, and platform-provided copies, not only package-manager records.

Remediate safely

  • Apply the maintained upstream correction or replace the affected component, then rebuild every dependent artifact from clean inputs.
  • Adopt bounds-checked interfaces, validated sizes and integer conversions, clear ownership, and memory-safe components where practical.
  • Enable supported compiler and runtime hardening and add sanitized tests and fuzz regression seeds derived from non-weaponized fixtures.

Authoritative sources

Complete CVE record and remediation plan

The detailed catalog view below loads this exact record, its source evidence, and the full seven-phase agentic change plan.