CVE-2026-33554: FreeIPMI Buffer Overflow Vulnerability

CVE-2026-33554 Overview

CVE-2026-33554 is a buffer overflow vulnerability affecting the ipmi-oem client command in FreeIPMI versions prior to 1.16.17. The Intelligent Platform Management Interface (IPMI) specification defines a set of interfaces for platform management and is implemented by numerous hardware manufacturers to support system management functions such as sensor reading (e.g., CPU temperatures) and remote power control.

The ipmi-oem command implements a set of IPMI OEM commands for specific hardware vendors. Three subcommands were found to contain exploitable buffer overflows when processing response messages from servers. These vulnerable subcommands are used to retrieve vendor-specific information from Dell, Supermicro, and Wistron servers.

Critical Impact
Attackers can exploit buffer overflows in IPMI OEM response message handling to cause denial of service conditions on systems running vulnerable FreeIPMI versions. Given that IPMI is commonly used for remote server management in data centers, successful exploitation could disrupt critical infrastructure management capabilities.

Affected Products

FreeIPMI versions prior to 1.16.17
Systems using ipmi-oem dell get-last-post-code command
Systems using ipmi-oem supermicro extra-firmware-info command
Systems using ipmi-oem wistron read-proprietary-string command

Discovery Timeline

2026-03-24 - CVE-2026-33554 published to NVD
2026-03-24 - Last updated in NVD database

Technical Details for CVE-2026-33554

Vulnerability Analysis

This vulnerability is classified as CWE-121 (Stack-based Buffer Overflow), which occurs when a buffer stored on the stack is overwritten by data that exceeds its allocated size. In the context of FreeIPMI, the buffer overflow vulnerabilities exist in the handling of response messages from IPMI OEM commands.

When a user executes one of the affected ipmi-oem subcommands to retrieve information from supported hardware, the client sends a request to the BMC (Baseboard Management Controller) and processes the response. The vulnerability manifests when the response message contains more data than the allocated buffers can accommodate, leading to memory corruption.

The network-accessible nature of this vulnerability is particularly concerning as IPMI interfaces are often exposed on management networks. An attacker who can send crafted responses to an IPMI client—either through a compromised BMC or via man-in-the-middle positioning—could trigger the buffer overflow condition.

Root Cause

The root cause of CVE-2026-33554 lies in insufficient bounds checking when processing IPMI OEM response messages. The three affected subcommands—get-last-post-code (Dell), extra-firmware-info (Supermicro), and read-proprietary-string (Wistron)—fail to properly validate the length of data received in response messages before copying it into fixed-size stack buffers.

This is a classic stack-based buffer overflow scenario where the application trusts the size of incoming data without proper validation. When response data exceeds the expected buffer size, it overwrites adjacent stack memory, potentially corrupting return addresses, saved registers, or other critical program state.

Attack Vector

The attack vector for this vulnerability requires network access to exploit. An attacker could potentially exploit this vulnerability through several scenarios:

Compromised BMC: If an attacker has already compromised a Baseboard Management Controller, they can send malicious IPMI response messages to any client attempting to query OEM-specific information.
Man-in-the-Middle Attack: An attacker positioned between the IPMI client and the BMC on the management network could intercept legitimate responses and replace them with crafted malicious payloads.
Rogue IPMI Endpoint: An attacker could set up a rogue IPMI endpoint that sends crafted responses when queried by the vulnerable ipmi-oem commands.

The vulnerability affects systems where administrators or automated tools use the FreeIPMI ipmi-oem command to gather vendor-specific information from Dell, Supermicro, or Wistron servers.

Detection Methods for CVE-2026-33554

Indicators of Compromise

Unexpected crashes or segmentation faults in ipmi-oem processes
Abnormal IPMI traffic patterns on management networks, particularly oversized response messages
Process termination logs indicating buffer overflow protection mechanisms (stack canary violations)
Core dump files generated by ipmi-oem command failures

Detection Strategies

Monitor system logs for ipmi-oem process crashes or abnormal terminations
Implement network intrusion detection rules to identify malformed IPMI response packets
Deploy endpoint detection to alert on unexpected ipmi-oem process behavior
Audit FreeIPMI installations across infrastructure to identify vulnerable versions prior to 1.16.17

Monitoring Recommendations

Enable process monitoring for FreeIPMI utilities on management systems
Implement network segmentation monitoring between management and production networks
Configure alerting for repeated ipmi-oem command failures in operational scripts
Review IPMI management network traffic for anomalous response message sizes

How to Mitigate CVE-2026-33554

Immediate Actions Required

Upgrade FreeIPMI to version 1.16.17 or later immediately
Audit systems for FreeIPMI installations using freeipmi --version or package manager queries
Restrict access to IPMI management networks to authorized personnel only
Temporarily disable usage of the affected ipmi-oem subcommands until patching is complete

Patch Information

The vulnerability has been addressed in FreeIPMI version 1.16.17. System administrators should upgrade to this version or later to remediate the buffer overflow vulnerabilities in the ipmi-oem command. The patched version is available from the GNU FreeIPMI Project.

Additional technical details about the individual vulnerabilities can be found in the GNU bug reports:

Workarounds

Avoid using the affected ipmi-oem subcommands (dell get-last-post-code, supermicro extra-firmware-info, wistron read-proprietary-string) until the patch is applied
Implement strict network access controls on IPMI management interfaces
Use alternative methods to retrieve the same information where possible
Consider implementing IPMI traffic inspection on management network boundaries

bash

# Verify FreeIPMI version and upgrade
freeipmi --version

# On Debian/Ubuntu systems
sudo apt update && sudo apt install freeipmi-tools

# On RHEL/CentOS systems
sudo yum update freeipmi

# Verify the upgrade
freeipmi --version
# Ensure version is 1.16.17 or later