CVE-2021-25134 – A buffer overflow vulnerability in the Baseboar... (How to Fix)

Q: What is the severity of CVE-2021-25134?

CVE-2021-25134 has a CVSS score of 7.8 (HIGH). A buffer overflow vulnerability in the Baseboard Management Controller (BMC) firmware for HPE Cloudline servers allows local attackers to execute arbitrary code or cause denial of service. This affects administrators or users with local access to the BMC interface. The vulnerability is in the spx_restservice setremoteimageinfo_func function.

📋 TL;DR

A buffer overflow vulnerability in the Baseboard Management Controller (BMC) firmware for HPE Cloudline servers allows local attackers to execute arbitrary code or cause denial of service. This affects administrators or users with local access to the BMC interface. The vulnerability is in the spx_restservice setremoteimageinfo_func function.

💻 Affected Systems

Products:

HPE Cloudline CL5800 Gen9 Server
HPE Cloudline CL5200 Gen9 Server
HPE Cloudline CL4100 Gen10 Server
HPE Cloudline CL3100 Gen10 Server
HPE Cloudline CL5800 Gen10 Server

Versions: BMC firmware versions prior to the patched version

Operating Systems: Not applicable - BMC firmware vulnerability

Default Config Vulnerable: ⚠️ Yes

Notes: Only affects the BMC firmware, not the host operating system. Requires access to the BMC management interface.

📦 What is this software?

⚠️ Risk & Real-World Impact

🔴

Worst Case

Full compromise of the BMC allowing persistent access, firmware modification, and potential lateral movement to the host operating system.

🟠

Likely Case

Local privilege escalation on the BMC leading to unauthorized configuration changes or denial of service.

🟢

If Mitigated

Limited impact if BMC access is restricted to trusted administrators and network segmentation is in place.

🌐 Internet-Facing: LOW (BMC interfaces should never be internet-facing)

🏢 Internal Only: MEDIUM (Requires local network access to BMC interface)

🎯 Exploit Status

Public PoC: ✅ No

Weaponized: UNKNOWN

Unauthenticated Exploit: ✅ No

Complexity: MEDIUM

Requires local access to the BMC interface. Buffer overflow exploitation typically requires some technical skill.

🛠️ Fix & Mitigation

✅ Official Fix

Patch Version: Refer to HPE advisory for specific patched firmware versions

Vendor Advisory: https://support.hpe.com/hpsc/doc/public/display?docLocale=en_US&docId=emr_na-hpesbhf04073en_us

Restart Required: Yes

Instructions:

1. Download the updated BMC firmware from HPE support portal
2. Access the BMC web interface
3. Navigate to firmware update section
4. Upload and apply the firmware update
5. The BMC will restart automatically

🔧 Temporary Workarounds

Restrict BMC network access

all

Limit access to BMC management interface to trusted administrative networks only

Configure firewall rules to restrict access to BMC IP addresses
Use VLAN segmentation for management networks

Disable unused BMC services

all

Disable REST service if not required for operations

Check BMC configuration for service disable options

🧯 If You Can't Patch

Isolate BMC management network from production networks
Implement strict access controls and monitoring for BMC interfaces

🔍 How to Verify

Check if Vulnerable:

Check BMC firmware version against HPE advisory. Access BMC web interface and check firmware version in system information.

Check Version:

ipmitool mc info (if IPMI is enabled) or check via BMC web interface

Verify Fix Applied:

Verify BMC firmware version matches or exceeds the patched version listed in HPE advisory.

📡 Detection & Monitoring

Log Indicators:

Unusual BMC authentication attempts
BMC firmware modification events
BMC service restart logs

Network Indicators:

Unusual traffic to BMC management ports (default 443/623)
Multiple failed authentication attempts to BMC

SIEM Query:

source="BMC" AND (event_type="authentication_failure" OR event_type="firmware_update")

📊 Metadata

CVE ID: CVE-2021-25134

CVSS v3 Score: 7.8 (HIGH)

CVSS Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

CWE: CWE-120

Published: January 29, 2021

Last Updated: November 21, 2024

🔗 References

https://support.hpe.com/hpsc/doc/public/display?docLocale=en_US&docId=emr_na-hpesbhf04073en_us Vendor Advisory
https://support.hpe.com/hpsc/doc/public/display?docLocale=en_US&docId=emr_na-hpesbhf04073en_us Vendor Advisory

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