Vulnerability in Linux Kernel

CVE-2023-4155

A flaw was found in KVM AMD Secure Encrypted Virtualization (SEV) in the Linux kernel. A KVM guest using SEV-ES or SEV-SNP with multiple vCPUs can trigger a double fetch race condition vulnerability and invoke the `VMGEXIT` handler recursively. If an attacker manages to call the handler multiple times, they can trigger a stack overflow and cause a denial of service or potentially guest-to-host escape in kernel configurations without stack guard pages (`CONFIG_VMAP_STACK`).

Vulnerability class: TOCTOU (Time-of-Check to Time-of-Use)

EPSS: 0.002 (5.5th percentile) — read the EPSS interpretation.