CVE-2026-2142 is an OS command injection vulnerability identified in the D-Link DIR-823X router firmware version 250416. The vulnerability resides in the function sub_420688 within the /goform/set_qos endpoint, which is responsible for Quality of Service (QoS) configuration. Due to improper input validation or sanitization, an attacker can remotely inject arbitrary operating system commands by manipulating requests to this endpoint. The attack vector is network-based (AV:N), requires no user interaction (UI:N), and no authentication (AT:N), making it highly accessible to remote attackers. The CVSS 4.0 vector indicates a high impact on confidentiality, integrity, and availability, with a score of 8.6. The vulnerability scope is limited to the affected router firmware version 250416. Although no active exploitation has been reported, the availability of a public exploit increases the risk of imminent attacks. Successful exploitation could allow attackers to execute arbitrary commands on the router, potentially leading to full device compromise, interception or manipulation of network traffic, lateral movement within the network, and disruption of services. The lack of patches or official mitigation guidance at the time of publication necessitates urgent defensive measures by administrators.

For European organizations, exploitation of CVE-2026-2142 could lead to severe consequences including unauthorized control over network infrastructure, interception of sensitive communications, and disruption of business-critical services. Compromised routers can serve as entry points for broader network intrusions, enabling attackers to pivot to internal systems or exfiltrate confidential data. The integrity of network traffic could be undermined, affecting trust in communications and potentially violating data protection regulations such as GDPR. Availability impacts could disrupt operations, especially for organizations relying on stable internet connectivity. Given the remote and unauthenticated nature of the exploit, large-scale automated attacks could target vulnerable devices across Europe, amplifying the threat. Critical sectors such as finance, healthcare, government, and telecommunications are particularly vulnerable due to their reliance on secure and reliable network infrastructure.

Immediate mitigation steps include isolating affected D-Link DIR-823X routers from untrusted networks and restricting access to the /goform/set_qos endpoint via firewall rules or network segmentation. Network administrators should monitor router logs for suspicious activity targeting QoS configuration interfaces. Since no official patches are currently available, organizations should contact D-Link support for firmware updates or advisories and apply them as soon as released. Employing network intrusion detection/prevention systems (IDS/IPS) with signatures for known exploit attempts can help detect and block attacks. As a longer-term measure, organizations should consider replacing vulnerable devices with models that have a strong security track record and timely vendor support. Additionally, enforcing strict network access controls and regularly auditing router configurations can reduce exposure to similar vulnerabilities.