CVE-2026-7067 Overview
A command injection vulnerability has been identified in the D-Link DIR-822 router running firmware version A_101. The vulnerability exists within the udhcpd DHCP Service component, specifically in the system function located in the /udhcpcd/dhcpd.c file. An attacker can exploit this flaw by manipulating the Hostname argument to inject arbitrary commands, which are then executed by the system.
This vulnerability is particularly concerning as it can be exploited remotely over the network without requiring any user interaction or authentication. The exploit has been publicly disclosed, increasing the risk of active exploitation in the wild.
Critical Impact
Remote command injection allowing attackers to execute arbitrary system commands on vulnerable D-Link DIR-822 routers via the DHCP Hostname parameter. This affects end-of-life products with no vendor support.
Affected Products
- D-Link DIR-822 Hardware Revision A1
- D-Link DIR-822 Firmware Version 1.0.1
- dlink dir-822_firmware
Discovery Timeline
- 2026-04-27 - CVE-2026-7067 published to NVD
- 2026-04-30 - Last updated in NVD database
Technical Details for CVE-2026-7067
Vulnerability Analysis
The vulnerability resides in the udhcpd DHCP service implementation on D-Link DIR-822 routers. When processing DHCP requests, the service improperly handles the Hostname field provided by DHCP clients. The vulnerable code path passes user-controlled hostname data directly to the system() function without adequate input sanitization or validation.
This creates a classic command injection scenario where an attacker on the local network (or any network that can reach the DHCP service) can craft a malicious DHCP request containing shell metacharacters in the Hostname field. When processed, these metacharacters break out of the intended command context, allowing arbitrary command execution with the privileges of the DHCP service process.
The impact includes full compromise of the router, enabling attackers to intercept network traffic, modify DNS settings, pivot to internal networks, or use the device as part of a botnet. This vulnerability only affects products that are no longer supported by D-Link, meaning no official patch will be released.
Root Cause
The root cause is improper input validation (CWE-74: Improper Neutralization of Special Elements in Output Used by a Downstream Component) in the DHCP hostname processing routine. The system() function in /udhcpcd/dhcpd.c accepts the Hostname argument without sanitizing shell metacharacters such as semicolons (;), backticks (`), dollar signs ($), or pipe characters (|). This allows command chaining and injection when a malicious hostname is provided in a DHCP request.
Attack Vector
The attack can be initiated remotely over the network. An attacker needs to be able to send DHCP requests to the vulnerable router's DHCP service. This can be achieved by:
- Connecting to the network served by the vulnerable router
- Sending a crafted DHCP DISCOVER or DHCP REQUEST packet with a malicious Hostname option
- The injected commands execute when the router processes the DHCP request
The attack requires no authentication and no user interaction, making it highly exploitable. The vulnerability mechanism involves shell metacharacter injection in the Hostname field that bypasses input validation. For detailed technical analysis and proof-of-concept information, refer to the Notion Security Analysis published by the security researcher.
Detection Methods for CVE-2026-7067
Indicators of Compromise
- Unusual DHCP hostnames containing shell metacharacters (;, |, `, $(), &&) in DHCP logs or packet captures
- Unexpected outbound connections from the router to external IP addresses
- Modified router configuration or DNS settings without administrator action
- Presence of unauthorized processes or binaries running on the router
- Abnormal network traffic patterns indicating command-and-control communication
Detection Strategies
- Monitor DHCP traffic for anomalous hostname values containing special characters or encoded payloads
- Deploy network intrusion detection systems (IDS) with signatures for DHCP command injection patterns
- Implement log analysis for the router's DHCP service looking for failed or suspicious hostname entries
- Use SentinelOne Singularity to detect post-exploitation behaviors on endpoints connected to compromised networks
Monitoring Recommendations
- Enable verbose logging on DHCP services where possible and forward logs to a SIEM
- Regularly audit router configurations for unauthorized changes
- Monitor for DNS hijacking attempts or suspicious DNS query patterns from network devices
- Implement network segmentation to limit the blast radius of IoT device compromises
How to Mitigate CVE-2026-7067
Immediate Actions Required
- Replace affected D-Link DIR-822 devices with currently supported router models as no patch will be provided
- If replacement is not immediately possible, disable the DHCP server on the vulnerable router and use an alternative DHCP solution
- Implement network segmentation to isolate vulnerable devices from critical network assets
- Enable firewall rules to restrict access to the router's management interfaces
Patch Information
D-Link has indicated that the DIR-822 hardware revision A1 is an end-of-life product and will not receive security updates. Users are strongly advised to retire these devices and replace them with currently supported models. For more information, visit the D-Link Official Website for current product offerings and security advisories.
Additional technical details are available at VulDB Vulnerability #359642.
Workarounds
- Disable the udhcpd DHCP service on the router and deploy a separate, secure DHCP server on the network
- Implement strict network access controls to limit which devices can send DHCP requests
- Use a dedicated firewall or security appliance in front of the vulnerable router to filter malicious DHCP traffic
- Consider deploying a VPN or network access control solution to authenticate devices before they can access DHCP services
# Example: Disable DHCP server via router CLI (if accessible)
# Note: This is a general example - actual commands may vary by firmware
config dhcp server disable
config save
reboot
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
