CVE-2023-45230: Tianocore EDK2 Buffer Overflow Vulnerability

CVE-2023-45230 Overview

EDK2's Network Package is susceptible to a buffer overflow vulnerability via a long server ID option in DHCPv6 client. This vulnerability can be exploited by an attacker to gain unauthorized access and potentially lead to a loss of Confidentiality, Integrity and/or Availability. The vulnerability is part of a collection of UEFI firmware flaws collectively known as "PixieFail" that affect the network stack implementation in the TianoCore EDK2 open-source UEFI reference implementation.

Critical Impact

This buffer overflow vulnerability in the DHCPv6 client allows adjacent network attackers to execute arbitrary code at the UEFI firmware level, potentially compromising system integrity before the operating system loads.

Affected Products

• Tianocore EDK2 (all versions prior to security patch)
• UEFI firmware implementations based on EDK2 Network Package
• Enterprise systems using PXE boot with EDK2-based firmware

Discovery Timeline

• 2024-01-16 - CVE-2023-45230 published to NVD
• 2025-11-04 - Last updated in NVD database

Technical Details for CVE-2023-45230

Vulnerability Analysis

The vulnerability exists in the DHCPv6 client implementation within EDK2's Network Package. When processing DHCPv6 server responses, the client fails to properly validate the length of the Server ID option before copying it into a fixed-size buffer. This improper restriction of operations within the bounds of a memory buffer (CWE-119) allows an attacker on the adjacent network to craft malicious DHCPv6 responses containing an oversized Server ID option.

The attack can be executed during the PXE (Preboot Execution Environment) boot process, which is commonly used in enterprise environments for network-based system provisioning. Since the vulnerability exists at the firmware level, successful exploitation occurs before the operating system loads, making it particularly dangerous as it can bypass traditional OS-level security controls.

Root Cause

The root cause of this vulnerability is improper bounds checking in the DHCPv6 client code when handling the Server ID option field. The code allocates a fixed-size buffer for the Server ID but does not validate that incoming data fits within this buffer before performing memory copy operations. This classic buffer overflow pattern allows attackers to write beyond the allocated memory region, corrupting adjacent memory structures and potentially achieving code execution.

Attack Vector

The attack requires the adversary to be on the same network segment as the target system (adjacent network access). The attacker must be able to send malicious DHCPv6 responses to a victim system during its PXE boot sequence. This can be achieved through:

1. Rogue DHCPv6 Server: Setting up a malicious DHCPv6 server on the local network that responds to client requests with crafted packets containing oversized Server ID options
2. Man-in-the-Middle: Intercepting legitimate DHCPv6 traffic and injecting malicious responses
3. Network Access: Gaining access to network segments where systems perform PXE boot operations

The vulnerability is particularly concerning in data center environments where PXE boot is commonly used for system deployment and recovery. Proof-of-concept exploits have been published as part of the PixieFail research, demonstrating the practical exploitability of this issue. For technical details, refer to the Packet Storm PoC publication.

Detection Methods for CVE-2023-45230

Indicators of Compromise

• Unusual DHCPv6 traffic patterns on network segments used for PXE boot operations
• DHCPv6 responses containing abnormally large Server ID options (exceeding expected bounds)
• Unexpected system crashes or hangs during the PXE boot process
• Anomalous network activity from systems during pre-boot phases

Detection Strategies

• Monitor network traffic for DHCPv6 packets with Server ID options exceeding normal size thresholds
• Implement network intrusion detection rules to identify malformed DHCPv6 responses
• Deploy network segmentation to isolate PXE boot traffic and enable focused monitoring
• Audit firmware versions across systems to identify those running vulnerable EDK2 implementations

Monitoring Recommendations

• Enable logging on DHCPv6 servers and network devices to capture suspicious client-server interactions
• Implement network flow analysis on segments where PXE boot operations occur
• Deploy SentinelOne agents to monitor for post-exploitation activities that may indicate firmware compromise
• Establish baseline network behavior for PXE boot operations to detect anomalies

How to Mitigate CVE-2023-45230

Immediate Actions Required

• Update EDK2-based firmware to the latest patched version from your hardware vendor
• Disable IPv6 network boot if not required for operations
• Segment networks to restrict access to PXE boot infrastructure
• Implement DHCPv6 snooping and guard features on network switches where available

Patch Information

TianoCore has released security patches addressing this vulnerability. Organizations should consult the GitHub Security Advisory GHSA-hc6x-cw6p-gj7h for detailed patch information and apply firmware updates from their respective hardware vendors. Additional vendor-specific guidance is available from NetApp, Fedora, and Debian. The CERT Vulnerability Note VU#132380 provides additional coordination details.

Workarounds

• Disable DHCPv6 and IPv6 PXE boot functionality in UEFI settings if not operationally required
• Implement strict network access controls on VLANs used for PXE boot operations
• Use static IPv4-based PXE configurations as an alternative to DHCPv6 where possible
• Deploy 802.1X port-based network access control to prevent unauthorized devices from sending malicious DHCPv6 responses

# Example: Disable IPv6 PXE boot in UEFI shell (system-specific)
# Consult your hardware vendor documentation for exact commands
# Generally, disable network boot or IPv6 stack in BIOS/UEFI settings

# Network-level mitigation: Configure DHCPv6 guard on Cisco switches
# interface range GigabitEthernet0/1-48
#   ipv6 dhcp guard policy DHCP_GUARD
#   ipv6 nd raguard