CVE-2026-5976: Totolink A7100RU Command Injection - PoC Available

Overview

A critical command injection vulnerability, CVE-2026-5976, affects the Totolink A7100RU wireless router. The flaw resides in the device’s web management interface, specifically within the setStorageCfg function of the /cgi-bin/cstecgi.cgi handler. Attackers can exploit this by sending a specially crafted network request to manipulate the sambaEnabled parameter, leading to arbitrary operating system command execution.

Technical Details

The vulnerability has a CVSS v3.1 base score of 9.8 (CRITICAL), stemming from its worst-case characteristics: it can be exploited over a network (Attack Vector: NETWORK) without requiring any user interaction or privileges (Privileges Required: NONE, User Interaction: NONE). The attack complexity is low, making exploitation straightforward. A public proof-of-concept (PoC) exploit is available, significantly lowering the barrier for attackers to weaponize this flaw. While not currently listed on CISA’s Known Exploited Vulnerabilities (KEV) catalog, the public PoC means attacks are now feasible and likely.

Impact

Successful exploitation allows an unauthenticated remote attacker to execute commands with the privileges of the web server process on the underlying router operating system. This can lead to a complete compromise of the device, enabling attackers to steal credentials, redirect traffic, install persistent malware, or use the router as a foothold into the internal network. All instances of the Totolink A7100RU running firmware version 7.4cu.2313_b20191024 are confirmed vulnerable.

Remediation and Mitigation

The primary remediation is to apply a firmware update from the vendor. Administrators should immediately check the Totolink support portal for a patched version of the firmware and upgrade all affected devices. If a patch is not immediately available, the following mitigation steps are critical:

• Restrict access to the router’s web management interface (port 80/443) to trusted internal networks only. Do not expose this interface to the internet.
• Implement network segmentation to limit the potential lateral movement from a compromised router.
• Monitor network traffic for anomalous outbound connections or unexpected configuration changes originating from network infrastructure devices.

For tracking related threats, recent data breach reports are available at breach reports and general updates at security news.

Security Insight

This vulnerability is a stark example of the persistent security challenges in consumer and SOHO network equipment, where CGI handlers often insecurely pass user input to system shells. It mirrors historical incidents in other vendors’ routers, highlighting a recurring pattern of insufficient input validation in device management APIs. The public release of a PoC for such a high-severity, network-based flaw will inevitably lead to scanning and exploitation attempts, placing the onus on users to seek out patches for devices that often lack automated update mechanisms.

Further Reading

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