What’s Vulnerable › Vulnerabilities

CVE-2021-4093

• Severity: high (CVSS 8.8 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.4% probability of exploitation in the next 30 days
• Public exploit or detection template: yes
• Published: 2022-02-18 · updated 2026-06-17
• Weakness: CWE-125

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.

Affected products

• Canonical Ubuntu Linux: 20.04, 21.10
• Fedoraproject Fedora: 35
• Linux kernel: from 5.11 before 5.14.16 — fixed in 5.14.16
• Red Hat Enterprise Linux: 8.0

How to fix

Upgrade to a fixed version: Linux kernel 5.14.16. Check the vendor advisory for mitigations.

References

• https://bugs.chromium.org/p/project-zero/issues/detail?id=2222
• https://bugzilla.redhat.com/show_bug.cgi?id=2028584
• https://bugs.chromium.org/p/project-zero/issues/detail?id=2222
• https://bugzilla.redhat.com/show_bug.cgi?id=2028584

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