CVE-2025-26336: Dell CMC PowerEdge FX2 RCE Vulnerability

CVE-2025-26336 Overview

CVE-2025-26336 is a stack-based buffer overflow vulnerability affecting Dell Chassis Management Controller (CMC) firmware for Dell PowerEdge FX2 and Dell PowerEdge VRTX systems. This firmware vulnerability allows an unauthenticated attacker with remote network access to potentially achieve remote code execution on vulnerable chassis management controllers.

The vulnerability exists in the firmware handling routines where improper bounds checking allows an attacker to overflow stack-allocated buffers. This type of vulnerability is particularly dangerous in infrastructure management components as these controllers have privileged access to server chassis operations, potentially allowing attackers to compromise multiple servers within a single chassis.

Critical Impact

Unauthenticated remote attackers can achieve remote code execution on Dell Chassis Management Controllers, potentially compromising entire server chassis infrastructure.

Affected Products

• Dell Chassis Management Controller Firmware for Dell PowerEdge FX2 (versions prior to 2.40.200.202101130302)
• Dell Chassis Management Controller Firmware for Dell PowerEdge VRTX (versions prior to 3.41.200.202209300499)
• Dell Chassis Management Controller for PowerEdge FX2 Hardware
• Dell Chassis Management Controller for PowerEdge VRTX Hardware

Discovery Timeline

• 2025-03-21 - CVE-2025-26336 published to NVD
• 2025-03-27 - Last updated in NVD database

Technical Details for CVE-2025-26336

Vulnerability Analysis

This vulnerability is classified under CWE-121 (Stack-based Buffer Overflow) and CWE-787 (Out-of-bounds Write). Stack-based buffer overflows occur when data written to a stack-allocated buffer exceeds its allocated size, overwriting adjacent memory including return addresses and saved frame pointers.

In the context of the Dell Chassis Management Controller, this vulnerability can be exploited remotely without any authentication requirements. The attack surface is accessible over the network, making it particularly dangerous for organizations with exposed management interfaces. Successful exploitation grants attackers the ability to execute arbitrary code in the context of the CMC firmware, which typically runs with elevated privileges to manage chassis operations.

The Dell CMC provides critical infrastructure management functions including power management, thermal monitoring, and server blade administration. Compromise of this component could allow attackers to manipulate power states, access sensitive configuration data, or pivot to attack individual server blades within the chassis.

Root Cause

The root cause is a stack-based buffer overflow resulting from inadequate input validation and bounds checking in the CMC firmware. When processing network input, the firmware fails to properly validate the size of data being written to fixed-size stack buffers. This allows an attacker to provide oversized input that overwrites adjacent stack memory, including critical control data such as return addresses.

Stack buffer overflows are a classic vulnerability class that can lead to arbitrary code execution when attackers carefully craft input to overwrite the saved return address with a pointer to attacker-controlled code or ROP gadgets.

Attack Vector

The attack vector is network-based and requires no authentication or user interaction. An attacker can remotely target the CMC's network interfaces to deliver malicious payloads designed to trigger the buffer overflow condition.

The attack flow typically involves:

1. Identifying an exposed Dell CMC management interface on the network
2. Crafting a malicious request containing oversized data to trigger the buffer overflow
3. Overwriting stack memory to redirect execution flow
4. Achieving arbitrary code execution on the CMC firmware

Because the vulnerability requires no authentication, any attacker with network access to the CMC interface can potentially exploit this vulnerability. This is particularly concerning for management interfaces that may be inadvertently exposed to untrusted networks.

Detection Methods for CVE-2025-26336

Indicators of Compromise

• Unusual network traffic patterns targeting Dell CMC management ports (typically HTTPS on port 443 or dedicated management ports)
• Unexpected CMC firmware crashes, reboots, or service interruptions
• Anomalous authentication failures or access patterns in CMC logs
• Unauthorized configuration changes to chassis or blade settings

Detection Strategies

• Deploy network intrusion detection systems (IDS/IPS) to monitor traffic to CMC management interfaces for malformed or oversized requests
• Implement firmware integrity monitoring to detect unauthorized modifications to CMC firmware
• Configure SIEM rules to correlate anomalous CMC activity with network-based attack indicators
• Perform regular vulnerability scans of infrastructure management components to identify unpatched systems

Monitoring Recommendations

• Enable comprehensive logging on Dell CMC interfaces and forward logs to centralized SIEM solutions
• Monitor for unexpected outbound connections from CMC devices that could indicate post-exploitation activity
• Implement network segmentation monitoring to detect lateral movement attempts from compromised management controllers
• Establish baseline behavior for CMC devices and alert on deviations

How to Mitigate CVE-2025-26336

Immediate Actions Required

• Identify all Dell PowerEdge FX2 and VRTX chassis in your environment and inventory their current CMC firmware versions
• Isolate CMC management interfaces from untrusted networks using network segmentation and firewall rules
• Prioritize firmware updates for any CMC devices accessible from less-trusted network segments
• Implement strict access control lists (ACLs) limiting which systems can communicate with CMC management interfaces

Patch Information

Dell has released security updates to address this vulnerability. Affected organizations should upgrade their CMC firmware to the following versions or later:

• Dell PowerEdge FX2: Firmware version 2.40.200.202101130302 or later
• Dell PowerEdge VRTX: Firmware version 3.41.200.202209300499 or later

For detailed patching instructions and firmware downloads, refer to the Dell Security Advisory DSA-2025-123.

Workarounds

• Restrict network access to CMC management interfaces using firewall rules, allowing only authorized management workstations
• Place CMC interfaces on dedicated, isolated management networks (out-of-band management)
• Implement jump servers or bastion hosts for accessing CMC interfaces, reducing direct network exposure
• Deploy network-based intrusion prevention systems (IPS) in front of management interfaces to filter potentially malicious traffic

# Example firewall rules to restrict CMC access (Linux iptables)
# Replace 192.168.100.0/24 with your authorized management network
# Replace 10.0.0.10 with your CMC IP address

iptables -A INPUT -d 10.0.0.10 -s 192.168.100.0/24 -p tcp --dport 443 -j ACCEPT
iptables -A INPUT -d 10.0.0.10 -p tcp --dport 443 -j DROP