CVE-2026-121930
Deferred Deferred - Pending Action

Command Injection in Linksys WRT54GL Router

Publication date: 2026-11-04

Last updated on: 2026-11-04

Assigner: VulDB

Description
A weakness has been identified in Linksys WRT54GL 4.30.18. The affected element is the function system of the file apply.cgi of the component Ping Diagnostic. This manipulation of the argument ping_ip causes os command injection. The attack can be initiated remotely. The exploit has been made available to the public and could be used for attacks. The vendor was contacted early about this disclosure but did not respond in any way. This vulnerability only affects products that are no longer supported by the maintainer.

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Meta Information

Published
2026-11-04
Last Modified
2026-11-04
Generated
2026-11-04
AI Q&A
2026-11-04
EPSS Evaluated
N/A
NVD
CVE-2026-121930
EUVD
EUVD-2026-117019

Affected Vendors & Products

Showing 1 associated CPE
Vendor Product Version / Range
Linksys WRT54GL 4.30.18

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Exploitability

CWE
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KEV
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CWE ID Description
CWE-78 The product constructs all or part of an OS command using externally-influenced input from an upstream component, but it does not neutralize or incorrectly neutralizes special elements that could modify the intended OS command when it is sent to a downstream component.
CWE-77 The product constructs all or part of a command using externally-influenced input from an upstream component, but it does not neutralize or incorrectly neutralizes special elements that could modify the intended command when it is sent to a downstream component.

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Executive Summary

This vulnerability is an authenticated OS command injection in the Linksys WRT54GL router firmware version 4.30.18. It occurs in the Ping Diagnostic function of the web management interface where the ping_ip parameter is passed unsafely into a shell command executed with root privileges. An attacker can inject arbitrary commands through this parameter by exploiting insufficient input validation.

Detection Guidance

To detect this vulnerability, check if your Linksys WRT54GL router (firmware 4.30.18) is exposed to the internet or accessible from your network. Use tools like curl or wget to send a crafted POST request to /apply.cgi with parameters submit_button=Ping, submit_type=start, and ping_ip set to a test payload like '127.0.0.1;id'. If the response includes command output or errors, the device is vulnerable.

Impact Analysis

This vulnerability allows an authenticated attacker to execute arbitrary commands with root privileges on the device. This could lead to full device compromise, configuration tampering, traffic interception, and potential persistence. The attack can be executed from the LAN or WAN if remote management is enabled.

Compliance Impact

This vulnerability allows authenticated attackers to execute arbitrary commands as root on the device, potentially leading to unauthorized access, data exfiltration, or configuration changes. For GDPR, this could result in unauthorized processing of personal data or breaches of confidentiality. For HIPAA, it may expose protected health information if the device is used in a healthcare environment. The lack of vendor support and public exploit availability increases the risk of non-compliance with security requirements in these standards.

Mitigation Strategies

Immediately disconnect the vulnerable Linksys WRT54GL router from your network or the internet. Disable remote management if enabled. Replace the device with a supported model or isolate it behind a firewall. Apply network segmentation to limit exposure. Monitor for unusual activity.

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