CVE-2026-1544 in DIR-823X
Summary
by MITRE • 01/29/2026
A security flaw has been discovered in D-Link DIR-823X 250416. Impacted is the function sub_41E2A0 of the file /goform/set_mode. Performing a manipulation of the argument lan_gateway results in os command injection. The attack is possible to be carried out remotely. The exploit has been released to the public and may be used for attacks. This vulnerability only affects products that are no longer supported by the maintainer.
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Analysis
by VulDB Data Team • 02/09/2026
The vulnerability identified as CVE-2026-1544 represents a critical command injection flaw within the D-Link DIR-823X 250416 router firmware, specifically targeting the web-based administrative interface. This issue manifests in the sub_41E2A0 function located within the /goform/set_mode file, which processes user input without adequate sanitization or validation. The vulnerability specifically affects the lan_gateway parameter, which is commonly used to configure the router's gateway settings. When an attacker manipulates this parameter through a specially crafted HTTP request, the system fails to properly escape or validate the input before executing system commands, creating a direct pathway for arbitrary code execution. The flaw exists at the application layer within the router's web server implementation, where user-supplied data flows directly into system command invocations without proper input filtering mechanisms.
This vulnerability operates under the Common Weakness Enumeration framework as CWE-78, which categorizes it as a "Improper Neutralization of Special Elements used in an OS Command ('OS Command Injection')" weakness. The attack vector is remotely exploitable, meaning that an unauthenticated attacker can leverage this flaw from outside the network perimeter without requiring physical access or prior authentication credentials. The exploitation process involves crafting malicious HTTP requests that target the vulnerable web form handler, specifically designed to inject OS commands through the lan_gateway parameter. The fact that this vulnerability has been publicly released as an exploit increases the immediate risk profile significantly, as it removes the requirement for advanced exploitation techniques and makes the attack accessible to a broader range of threat actors. The vulnerability's remote nature and the availability of public exploit code transforms it from a theoretical security concern into an active threat that could be weaponized for network compromise.
The operational impact of this vulnerability extends beyond simple command execution, as it provides attackers with complete control over the affected router's operating system. This level of access enables adversaries to modify router configurations, establish persistent backdoors, redirect network traffic, and potentially use the compromised device as a pivot point for attacking other systems within the local network. The vulnerability's effect is particularly severe because routers serve as critical network infrastructure components, often acting as gateways between internal networks and the internet. Attackers could leverage this compromise to conduct man-in-the-middle attacks, monitor network traffic, or use the device as a launching point for broader network reconnaissance and penetration testing activities. The compromised router could also be used to distribute malware to connected devices or to establish command and control channels for further malicious activities. Given that this vulnerability affects unsupported products, victims may not receive security updates or patches, leaving them permanently exposed to this threat vector.
Mitigation strategies for CVE-2026-1544 should prioritize immediate hardware replacement or firmware updates where possible, though the affected product line is no longer supported by the vendor. Network administrators should implement strict firewall rules to restrict access to the router's administrative interface from untrusted networks, though this measure is only partially effective given the remote nature of the vulnerability. The implementation of network segmentation and monitoring solutions can help detect anomalous traffic patterns that might indicate exploitation attempts. Organizations should also consider deploying intrusion detection systems that can identify malicious requests targeting the specific vulnerable endpoint /goform/set_mode. For those unable to replace the affected hardware, implementing network access controls that limit who can access the router's administrative interface and regularly monitoring router logs for suspicious configuration changes can provide some protection. The vulnerability's classification as a critical security issue aligns with ATT&CK framework techniques such as T1059.001 for command and scripting interpreter and T1021.001 for remote services, highlighting the need for comprehensive network security controls and regular vulnerability assessments to prevent unauthorized access to critical network infrastructure components.