Comprehensive Threat Exposure Management Platform
CVE-2026-0625 is a critical security vulnerability affecting multiple legacy D-Link DSL router models, representing a severe threat that has persisted for over a decade. This CVE-2026-0625 command injection flaw resides in the DNS configuration endpoint of D-Link DSL-2740R, DSL-2640B, DSL-2780B, and DSL-526B routers, allowing remote attackers to achieve complete system compromise through poorly validated DNS input parameters.
The CVE-2026-0625 vulnerability enables threat actors to inject and execute system-level commands by exploiting weak input validation in the dnscfg.cgi endpoint. Attackers can gain root-level access to affected D-Link routers without requiring authentication or user interaction, making mass automated exploitation highly feasible. The critical nature of CVE-2026-0625 is compounded by confirmed active exploitation observed in late 2025, with attack patterns showing strong similarities to historical DNSChanger and GhostDNS campaigns that operated between December 2016 and January 2019.
The most alarming aspect of CVE-2026-0625 is that all affected D-Link DSL router models reached end-of-life status in early 2020 and will never receive security patches from the manufacturer. Organizations and individuals continuing to operate these vulnerable D-Link DSL gateways face severe and ongoing security risks including traffic interception, malware deployment, credential theft, and network pivoting. D-Link strongly recommends immediate retirement and replacement of all affected devices, as continued operation represents an unacceptable security exposure.
CVE-2026-0625 is a critical command injection vulnerability located in the dnscfg.cgi endpoint that exists across multiple legacy D-Link DSL gateway router models. This dnscfg.cgi endpoint processes DNS configuration requests submitted through the router’s web-based management interface, which is a standard feature allowing administrators to configure Domain Name System server settings for devices on the local network. The fundamental security flaw in CVE-2026-0625 originates from catastrophically weak input validation, where user-supplied DNS configuration parameters are not properly sanitized or validated before being processed by the underlying Linux-based router operating system.
The lack of input sanitization in CVE-2026-0625 creates a direct pathway for command injection attacks. Attackers can craft specially designed HTTP requests that embed malicious shell command sequences within what should be benign DNS configuration fields. When the vulnerable dnscfg.cgi endpoint processes these malicious requests, the embedded commands are passed directly to the device’s Unix shell and executed with the same privilege level as the web service process. On embedded Linux-based router firmware like that found in affected D-Link DSL models, the web service typically operates with root-level privileges, meaning CVE-2026-0625 exploitation grants attackers complete administrative control over the compromised router.
The severity of CVE-2026-0625 is dramatically amplified by the fact that the vulnerable dnscfg.cgi endpoint is accessible without any authentication requirements. Unlike vulnerabilities that require attackers to first compromise valid administrative credentials or trick authenticated users into performing specific actions, CVE-2026-0625 can be exploited through unauthenticated remote HTTP requests. Attackers do not need valid usernames, passwords, or any form of credential to exploit CVE-2026-0625 successfully. A simple crafted HTTP request sent to the vulnerable endpoint is sufficient to trigger command injection and achieve full router compromise.
This unauthenticated exploitation capability makes CVE-2026-0625 ideal for large-scale automated attacks targeting internet-facing D-Link DSL routers. Threat actors can scan the internet for vulnerable devices, identify D-Link DSL routers by their management interface fingerprints, and automatically exploit CVE-2026-0625 across thousands of devices with minimal effort. The combination of no authentication requirements and command injection leading to root access makes CVE-2026-0625 an extremely attractive target for botnet operators, ransomware distributors, and advanced persistent threat actors seeking to compromise network infrastructure.
CVE-2026-0625 demonstrates concerning similarities to previous DNS-focused attack campaigns against consumer routers, particularly the DNSChanger campaign that commenced in December 2016 and the GhostDNS infrastructure exploitation observed in January 2019. Both historical campaigns abused router DNS configuration capabilities to redirect victim traffic for phishing, advertising fraud, and credential theft operations. However, CVE-2026-0625 represents a far more dangerous evolution beyond simple DNS manipulation, enabling complete command execution and persistent device takeover capabilities.
Active exploitation of CVE-2026-0625 has been confirmed in the wild, with security researchers observing attack activity targeting vulnerable D-Link DSL endpoints in late 2025. This confirmed exploitation indicates that threat actors are already aware of CVE-2026-0625 and have developed weaponized exploits capable of targeting affected devices at scale. The exploitation patterns observed align with sophisticated threat actor methodologies focused on compromising network infrastructure devices to intercept traffic, deploy malware, harvest credentials, and establish persistent footholds for lateral movement into connected networks.
The full system compromise enabled by CVE-2026-0625 provides attackers with extensive capabilities including the ability to intercept and manipulate all network traffic flowing through the compromised router, deploy additional malware payloads to both the router and downstream connected devices, modify DNS settings to redirect victims to phishing sites or malicious servers, harvest credentials and sensitive data passing through the network, and use the compromised router as a pivot point for attacking other systems on the local network.
The most critical aspect of CVE-2026-0625 is the complete absence of remediation options. All affected D-Link DSL router models including DSL-526B, DSL-2640B, DSL-2740R, and DSL-2780B reached end-of-life and end-of-service status in early 2020, approximately six years before CVE-2026-0625 was publicly disclosed. D-Link has explicitly stated that these legacy products will not receive firmware updates or security patches of any kind. Organizations and individuals continuing to operate these vulnerable devices face ongoing critical security risks with no mitigation available beyond complete device replacement. D-Link strongly advises immediate retirement of all affected DSL gateway routers and replacement with currently supported models that receive regular security updates.
Organizations must conduct an immediate and comprehensive audit to identify all D-Link DSL-526B, DSL-2640B, DSL-2740R, and DSL-2780B devices deployed within their network environments. This CVE-2026-0625 vulnerability assessment should document the network locations of vulnerable routers, their current configurations, connectivity to critical systems and sensitive data resources, and the number of downstream users or devices depending on each vulnerable gateway. Asset inventory for CVE-2026-0625 remediation should prioritize routers with direct internet exposure, those providing network access to sensitive environments, and any devices serving critical infrastructure or production systems.
While device replacement is the only permanent solution for CVE-2026-0625, organizations requiring time to procure replacement equipment should immediately implement network segmentation to contain potential compromise. Vulnerable D-Link DSL routers affected by CVE-2026-0625 should be isolated from critical network assets through additional firewall controls placed between the vulnerable gateway and sensitive systems. Network isolation for CVE-2026-0625 mitigation should place affected routers in quarantined network zones with strict access controls limiting potential lateral movement in the event of successful exploitation.
Security teams should immediately verify current DNS server configurations on all D-Link DSL routers affected by CVE-2026-0625 to identify potential prior compromise. DNS settings should be checked for unauthorized or suspicious DNS servers that may indicate attackers have already exploited CVE-2026-0625 to redirect traffic. Legitimate DNS configurations typically use trusted public DNS providers such as Google Public DNS (8.8.8.8 and 8.8.4.4), Cloudflare DNS (1.1.1.1), or DNS servers provided by the organization’s internet service provider. Any unexpected or unfamiliar DNS server addresses discovered during CVE-2026-0625 assessment should be treated as indicators of compromise requiring immediate investigation and incident response.
Organizations must develop and execute a prioritized replacement schedule for all D-Link DSL gateways affected by CVE-2026-0625. Device replacement planning should procure modern router models from vendors with strong security track records and active support commitments, prioritizing devices that receive regular firmware updates and security patches. Replacement routers should be configured with strong unique administrative passwords, disable unnecessary remote management features, and implement current security best practices including disabling WPS, enabling WPA3 encryption where supported, and changing default credentials immediately upon deployment.
While factory resets do not eliminate the underlying CVE-2026-0625 vulnerability, organizations unable to immediately replace affected devices should perform factory resets to remove potential existing compromises. After factory reset, affected D-Link routers should be reconfigured with strong unique administrative passwords different from any previously used credentials, verified DNS settings pointing only to trusted providers, and disabled remote management features to reduce the attack surface. Organizations must understand that factory reset is only a temporary risk reduction measure and does not protect against future CVE-2026-0625 exploitation attempts.
Organizations should establish formal policies requiring immediate retirement of network infrastructure devices upon reaching end-of-life status from manufacturers. End-of-life policies for CVE-2026-0625 prevention should include proactive tracking of vendor support timelines for all network equipment, automated alerting when devices approach end-of-support dates, budget allocation for regular infrastructure refresh cycles, and prohibition of deploying or continuing to operate unsupported devices in production environments. Implementing comprehensive end-of-life policies ensures organizations avoid future situations where critical vulnerabilities like CVE-2026-0625 affect infrastructure with no remediation options available.
T1190 – Exploit Public-Facing Application: CVE-2026-0625 is exploited through the public-facing web management interface of vulnerable D-Link DSL routers. Attackers target the dnscfg.cgi endpoint accessible over HTTP/HTTPS without authentication, making this a classic example of exploiting internet-facing applications to gain initial access to target networks.
T1059 – Command and Scripting Interpreter: The core exploitation mechanism of CVE-2026-0625 involves injecting and executing arbitrary commands through command interpreters on the vulnerable D-Link routers.
T1059.004 – Unix Shell: CVE-2026-0625 exploitation passes malicious commands to the Unix shell running on the embedded Linux operating system of affected D-Link DSL routers, achieving code execution with root-level privileges through shell command injection.
T1588 – Obtain Capabilities: Threat actors exploiting CVE-2026-0625 must first obtain or develop exploitation capabilities including knowledge of the vulnerability, crafted HTTP requests for command injection, and automated scanning tools to identify vulnerable D-Link routers.
T1588.006 – Vulnerabilities: Attackers leveraging CVE-2026-0625 specifically acquire knowledge of this zero-day command injection vulnerability affecting legacy D-Link DSL gateway routers.
T1584 – Compromise Infrastructure: Successful exploitation of CVE-2026-0625 allows attackers to compromise network infrastructure devices for use in subsequent attack operations.
T1584.002 – DNS Server: Attackers exploiting CVE-2026-0625 can modify DNS server configurations on compromised routers, effectively compromising DNS infrastructure to redirect victim traffic as observed in DNSChanger and GhostDNS campaigns.
https://www.vulncheck.com/advisories/dlink-dsl-command-injection-via-dns-configuration-endpoint
https://supportannouncement.us.dlink.com/security/publication.aspx?name=SAP10488
https://supportannouncement.us.dlink.com/announcement/publication.aspx?name=SAP10068
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