CVE-2026-23131: Linux Kernel Kobject Registration Flaw

CVE-2026-23131 Overview

A vulnerability has been identified in the Linux kernel's hp-bioscfg driver that can cause kernel warnings when attempting to register kobjects with empty names. The issue occurs when the HP BIOS returns attributes with empty name strings, and the driver attempts to process them without proper validation.

When exploited, this vulnerability triggers multiple kernel warnings in the kobject subsystem, potentially impacting system stability and logging integrity on affected HP systems running the vulnerable kernel driver.

Critical Impact

The hp-bioscfg driver may generate kernel warnings and fail to properly register BIOS configuration attributes, potentially affecting system management capabilities on HP hardware.

Affected Products

• Linux kernel with hp-bioscfg driver enabled
• HP systems with WMI-based BIOS configuration interfaces
• Platform x86 subsystem configurations utilizing hp-bioscfg

Discovery Timeline

• 2026-02-14 - CVE CVE-2026-23131 published to NVD
• 2026-02-18 - Last updated in NVD database

Technical Details for CVE-2026-23131

Vulnerability Analysis

This vulnerability exists in the hp-bioscfg driver within the Linux kernel's platform/x86 subsystem. The driver is responsible for managing HP BIOS configuration attributes through the Windows Management Instrumentation (WMI) interface.

The core issue stems from insufficient input validation when processing BIOS attributes retrieved from HP's WMI buffer. When the HP BIOS returns attributes containing empty name strings, the driver proceeds to register these as kobjects without checking for validity. The Linux kernel's kobject subsystem requires non-empty names for registration, triggering warning messages when this invariant is violated.

The resulting kernel warnings appear as:

kobject: (00000000135fb5e6): attempted to be registered with empty name!
WARNING: CPU: 14 PID: 3336 at lib/kobject.c:219 kobject_add_internal+0x2eb/0x310

While this is primarily a stability and logging issue rather than a security vulnerability with direct exploitation potential, repeated kernel warnings can impact system performance and may mask other security-relevant log entries.

Root Cause

The root cause is a missing input validation check in the hp_init_bios_buffer_attribute() function. The function parses attribute names from the WMI buffer provided by the HP BIOS but does not verify that the parsed name string is non-empty before attempting to register the corresponding kobject with the kernel's sysfs subsystem.

This represents an improper input validation flaw where data from an external source (the BIOS WMI interface) is trusted without adequate sanitization.

Attack Vector

The attack vector for this vulnerability is limited. Exploitation would require:

1. An HP system with the hp-bioscfg driver loaded
2. The HP BIOS to return attribute entries with empty name strings (either through BIOS misconfiguration or manipulation)

In most scenarios, this vulnerability manifests as a bug triggered by malformed BIOS data rather than a remotely exploitable security flaw. The primary impact is system instability through kernel warning spam rather than direct security compromise.

The vulnerability does not require user interaction and is triggered automatically when the driver initializes and queries the BIOS for configuration attributes.

Detection Methods for CVE-2026-23131

Indicators of Compromise

• Kernel log messages containing "attempted to be registered with empty name!" from the kobject subsystem
• Warnings at lib/kobject.c:219 referencing kobject_add_internal function
• Repeated kernel warnings during hp-bioscfg module initialization
• Sysfs registration failures for HP BIOS configuration attributes

Detection Strategies

• Monitor kernel logs (dmesg or /var/log/kern.log) for kobject registration warnings
• Create alerting rules for WARNING messages originating from kobject_add_internal
• Check for hp-bioscfg module errors during system boot or module loading
• Implement system audit logging for kernel warning patterns

Monitoring Recommendations

• Deploy centralized log monitoring to capture kernel warnings across HP fleet systems
• Configure SentinelOne agents to detect anomalous kernel warning patterns
• Enable kernel debug logging on suspected affected systems for deeper analysis
• Review system stability metrics for correlation with driver loading events

How to Mitigate CVE-2026-23131

Immediate Actions Required

• Update to a patched Linux kernel version that includes the fix for hp_init_bios_buffer_attribute()
• If immediate patching is not possible, consider temporarily unloading the hp-bioscfg module using modprobe -r hp-bioscfg
• Review kernel logs for evidence of exploitation and assess system stability
• Prioritize patching on HP systems actively using BIOS configuration management features

Patch Information

The fix adds validation in hp_init_bios_buffer_attribute() to check if the attribute name is empty after parsing it from the WMI buffer. If the name is empty, the driver now logs a debug message and skips registration of that attribute, allowing the module to continue processing other valid attributes without triggering kernel warnings.

Multiple patch commits are available in the kernel git repository:

• Kernel Git Commit 29917c8
• Kernel Git Commit 6476be5
• Kernel Git Commit 800b276
• Kernel Git Commit fdee1b0

Workarounds

• Blacklist the hp-bioscfg module by adding blacklist hp-bioscfg to /etc/modprobe.d/blacklist.conf if the BIOS configuration feature is not required
• Unload the module from running systems using modprobe -r hp-bioscfg until a patched kernel can be deployed
• Monitor for kernel warnings and assess impact on affected systems while awaiting patching
• Consider firmware/BIOS updates from HP that may resolve underlying malformed attribute data

# Configuration example - Blacklist hp-bioscfg module until patched
echo "blacklist hp-bioscfg" | sudo tee /etc/modprobe.d/hp-bioscfg-blacklist.conf

# Unload module if currently loaded
sudo modprobe -r hp-bioscfg

# Verify module is not loaded
lsmod | grep hp-bioscfg