CVE-2026-23084: Linux Kernel Buffer Overflow Vulnerability

CVE-2026-23084 Overview

A NULL pointer dereference vulnerability has been identified in the Linux kernel's be2net network driver. The vulnerability exists in the be_cmd_get_mac_from_list() function, which can be triggered when the pmac_id_valid parameter is set to false while simultaneously passing a NULL pointer for the pmac_id argument. This violates the function's expected contract and can result in a kernel crash or system instability.

Critical Impact

Local attackers with access to affected systems could trigger a denial of service condition by exploiting this NULL pointer dereference in the be2net network driver.

Affected Products

• Linux kernel with be2net driver enabled
• Systems using Emulex/Broadcom network adapters supported by be2net
• Multiple kernel stable branches (see patch commits)

Discovery Timeline

• February 4, 2026 - CVE CVE-2026-23084 published to NVD
• February 5, 2026 - Last updated in NVD database

Technical Details for CVE-2026-23084

Vulnerability Analysis

The vulnerability stems from a violation of the function contract for be_cmd_get_mac_from_list() within the be2net network driver. This function is designed to request a PMAC_ID from the network card's firmware when the pmac_id_valid parameter is set to false. Under this condition, the function expects a valid memory address in the pmac_id parameter where it can store the retrieved PMAC_ID value.

The problematic code path occurs at a specific location within the driver where both pmac_id_valid == false and pmac_id == NULL are passed to the function. When the function attempts to dereference the NULL pointer to store the PMAC_ID value retrieved from firmware, a NULL pointer dereference occurs, potentially causing a kernel panic or system crash.

Root Cause

The root cause is improper input validation and a violation of the implicit contract of be_cmd_get_mac_from_list(). The calling code fails to provide a valid memory address for the pmac_id parameter when requesting the PMAC_ID from firmware. The function does not perform defensive NULL checking before dereferencing the pointer, assuming callers will always provide valid addresses when pmac_id_valid is false.

Attack Vector

The vulnerability requires local access to a system running an affected Linux kernel with the be2net driver loaded. An attacker with sufficient privileges to interact with the network driver or trigger the specific code path could cause a denial of service condition. The attack vector involves triggering the vulnerable code path where the incorrect parameters are passed to be_cmd_get_mac_from_list().

The fix implemented by the kernel maintainers involves passing the address of a stub variable to the function instead of NULL. This ensures the function always has a valid memory location to write the PMAC_ID, preventing the NULL pointer dereference.

For technical details on the fix, refer to the kernel git commit 31410a01.

Detection Methods for CVE-2026-23084

Indicators of Compromise

• Unexpected kernel panics or system crashes related to the be2net driver
• Kernel oops messages referencing be_cmd_get_mac_from_list or NULL pointer dereference
• System instability when network operations are performed on Emulex/Broadcom network adapters
• Crash dumps indicating issues in the be2net kernel module

Detection Strategies

• Monitor kernel logs for NULL pointer dereference errors associated with the be2net module
• Implement kernel crash monitoring with automatic alerting for unexpected reboots
• Deploy SentinelOne Singularity platform for real-time kernel-level threat detection
• Use kernel debugging tools like KASAN (Kernel Address Sanitizer) to detect memory access violations

Monitoring Recommendations

• Enable kernel auditing to track driver loading and network device operations
• Configure centralized logging for kernel messages to detect patterns of driver failures
• Implement system monitoring to alert on unexpected network driver crashes or reloads
• Review system stability reports for patterns that may indicate exploitation attempts

How to Mitigate CVE-2026-23084

Immediate Actions Required

• Update to patched kernel versions that include the fix for CVE-2026-23084
• Apply the relevant stable kernel patches from the kernel.org repositories
• Prioritize systems with Emulex/Broadcom network adapters using the be2net driver
• Consider temporary workarounds if immediate patching is not possible

Patch Information

The Linux kernel maintainers have released patches across multiple stable branches. The fix involves passing a stub variable address to be_cmd_get_mac_from_list() instead of NULL, ensuring the function always has a valid memory location for storing the PMAC_ID.

Patches are available through the following kernel git commits:

• Kernel Git Commit 31410a01
• Kernel Git Commit 47ffb4dc
• Kernel Git Commit 82157944
• Kernel Git Commit e206fb41

Workarounds

• If the be2net driver is not required, consider blacklisting the module to prevent loading
• Limit local access to affected systems to trusted administrators only
• Monitor affected systems closely for signs of instability until patches can be applied
• Consider using alternative network adapters if available until the vulnerability is patched

# Blacklist be2net driver if not required (temporary workaround)
echo "blacklist be2net" | sudo tee /etc/modprobe.d/blacklist-be2net.conf
sudo update-initramfs -u