CVE-2026-31561
Description
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.
Statement
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.
Mitigation
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.
Common Vulnerability Scoring System (CVSS) Score Details
Info alert:Important note
CVSS scores for open source components depend on vendor-specific factors (e.g. version or build chain). Therefore, Red Hat's score and impact rating can be different from NVD and other vendors. Red Hat remains the authoritative CVE Naming Authority (CNA) source for its products and services (see Red Hat classifications).
The following CVSS metrics and score provided are preliminary and subject to review.
CVSS v3 Score Breakdown
| Red Hat | NVD | cve.org | |
|---|---|---|---|
| Base Score | 5.5 | 5.5 | N/A |
| Attack Vector | Local | Local | N/A |
| Attack Complexity | Low | Low | N/A |
| Privileges Required | Low | Low | N/A |
| User Interaction | None | None | N/A |
| Scope | Unchanged | Unchanged | N/A |
| Confidentiality | None | None | N/A |
| Integrity Impact | None | None | N/A |
| Availability Impact | High | High | N/A |
Vector
Red Hat: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
NVD: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
Understanding the Weakness (CWE)
Other
Technical Impact: Varies by Context
Frequently Asked Questions
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