CVE-2026-31561

A flaw was found in the Linux kernel's handling of the CR4 pinned bits mask for FRED (Flexible Return and Event Delivery). An attacker could exploit this by modifying a specific bit in memory to disable CR4 pinning, potentially leading to a system crash. This vulnerability could result in a Denial of Service (DoS) for affected systems.

This Moderate impact flaw in the Linux kernel's handling of the CR4 pinned bits mask for Flexible Return and Event Delivery (FRED) can lead to a denial of service. Specifically, during system boot, an attacker could manipulate a memory bit to disable CR4 pinning, causing a system crash. This issue primarily affects Red Hat Enterprise Linux 6, 10, and Red Hat In-Vehicle OS 2, particularly impacting SEV-{ES,SNP} or TDX virtualized guests during FRED initialization.

The CVSS score(s) listed for this vulnerability do not reflect the associated product's status, and are included for informational purposes to better understand the severity of this vulnerability.

Mitigation for this issue is either not available or the currently available options do not meet the Red Hat Product Security criteria comprising ease of use and deployment, applicability to widespread installation base, or stability.