Executive Summary

CVE-2026-2175 is a remote OS command injection vulnerability found in the D-Link DIR-823X router, firmware version 250416. It affects the /goform/set_upnp endpoint, specifically the function sub_420618, which processes the upnp_enable parameter. The vulnerability arises because the input validation fails to filter newline characters, allowing an authenticated attacker to inject newline characters that prematurely terminate the intended configuration command and append arbitrary shell commands.

These injected commands are executed with root privileges, giving the attacker full control over the device. The attack requires authentication but can be performed remotely. A proof-of-concept exploit is publicly available, making exploitation easier.

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Impact Analysis

This vulnerability allows an authenticated attacker to execute arbitrary OS commands with root privileges on the affected router. This can lead to complete compromise of the device, including unauthorized access, modification, or disruption of network traffic.

• Full control over the router device.
• Compromise of confidentiality, integrity, and availability of the device.
• Potential for further attacks on the internal network.
• No known mitigations currently exist, increasing risk.

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Compliance Impact

I don't know

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Detection Guidance

[{'type': 'paragraph', 'content': 'This vulnerability can be detected by testing the /goform/set_upnp endpoint on the D-Link DIR-823X router firmware version 250416 for command injection via the upnp_enable parameter.'}, {'type': 'paragraph', 'content': 'Detection involves sending authenticated POST requests to the /goform/set_upnp endpoint with specially crafted payloads that include newline characters to attempt command injection.'}, {'type': 'paragraph', 'content': 'A proof-of-concept Python script exists that performs the following steps: authenticates to the router, injects commands via the upnp_enable parameter, and verifies command execution (e.g., by using sleep delays).'}, {'type': 'paragraph', 'content': 'Suggested detection commands or methods include:'}, {'type': 'list_item', 'content': 'Send an authenticated POST request to /goform/set_upnp with upnp_enable set to a payload like: 1"\\n\\necho test_command'}, {'type': 'list_item', 'content': 'Observe if the injected command (e.g., echo test_command) is executed on the device, indicating vulnerability.'}, {'type': 'list_item', 'content': 'Use the PoC Python script from Resource 3 to automate detection by performing login, token retrieval, and payload injection.'}] [3]

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Mitigation Strategies

[{'type': 'paragraph', 'content': 'Currently, no official patches or vendor mitigations are available for this vulnerability.'}, {'type': 'paragraph', 'content': 'Immediate mitigation steps include:'}, {'type': 'list_item', 'content': "Restrict access to the router's management interface to trusted networks and users only, minimizing exposure."}, {'type': 'list_item', 'content': 'Disable remote management features if possible to prevent remote exploitation.'}, {'type': 'list_item', 'content': 'Implement strict input validation or filtering on the upnp_enable parameter if you have the capability to modify the firmware or configuration.'}, {'type': 'list_item', 'content': 'Replace the affected device with an alternative product that is not vulnerable.'}, {'type': 'paragraph', 'content': 'Suggested technical mitigations from Resource 3 include implementing strict whitelisting (allowing only 0 or 1 for upnp_enable), expanding blacklist filters to reject newline and other shell metacharacters, replacing shell command execution with native API calls, and adding rigorous input validation.'}] [2, 3]

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