CVE-2024-40891 is a high-severity vulnerability affecting several Zyxel DSL Customer Premises Equipment (CPE) devices. This vulnerability allows authenticated attackers to execute operating system commands on the affected devices via Telnet, potentially leading to a full compromise of the device's operating system. Given the nature of this vulnerability, organizations utilizing these devices should treat it with urgency.
The CVSS score of 8.8 indicates a high level of risk, making it essential for organizations to prioritize remediation efforts. The vulnerability is classified under CWE-78, denoting its nature as a command injection issue. Zyxel has acknowledged this vulnerability, and it has been included in the Known Exploited Vulnerabilities (KEV) catalog, which signifies the potential for active exploitation in the wild.
Organizations should prioritize patching immediately. The exploitation of this vulnerability could lead to unauthorized access, data theft, and further network compromise, thus representing a significant threat to organizational security.
Given the critical nature of this vulnerability, it is imperative that affected organizations take immediate steps to assess their exposure and implement necessary security measures.
Vulnerability Details
The vulnerability described in CVE-2024-40891 is a post-authentication command injection flaw found in the management commands of the legacy Zyxel VMG4325-B10A firmware version 1.00(AAFR.4)C0_20170615. An authenticated attacker can exploit this vulnerability to execute arbitrary operating system commands on the affected device through Telnet.
The CVSS score for this vulnerability is 8.8 (high severity), indicating significant potential impact on the confidentiality, integrity, and availability of the affected systems. Organizations using any of the affected firmware versions should be aware that this vulnerability could lead to serious consequences if not addressed promptly.
The vulnerability affects various Zyxel firmware versions, including those for the SBG3300, SBG3500, and VMG series devices. It was published on February 4, 2025, and has been categorized under CWE-78, which pertains to OS command injection.
Technical Analysis
The root cause of CVE-2024-40891 lies in insufficient input validation within the management commands of the Zyxel firmware. This flaw allows attackers, who have already authenticated, to inject malicious commands that the device executes with operating system privileges. The attack vector is network-based, and the complexity of the attack is low, as it requires minimal effort on the part of the attacker.
The nature of the vulnerability requires low privileges for exploitation, and no user interaction is needed, making it particularly dangerous. The impact on confidentiality, integrity, and availability is rated as high, indicating that successful exploitation could lead to complete control over the device.
Risk & Impact Analysis
The real-world deployment risk associated with CVE-2024-40891 is significant. Organizations using affected Zyxel DSL CPE devices may face a high blast radius, as the vulnerability could be exploited to compromise entire networks, leading to unauthorized access to sensitive data and potential further intrusions.
The urgency for organizations to address this vulnerability is underscored by its inclusion in the KEV catalog and the high likelihood of exploitation. Organizations should assess their current device deployments and take immediate action to mitigate risks.
Failure to act may result in not only data loss but also reputational damage and regulatory repercussions, particularly for organizations in sensitive industries.
Exploitation Status
Signal | Status |
|---|---|
Known Exploit | No |
Public PoC | No |
Actively Exploited | Yes |
Ransomware Use | No |
Affected Versions
The affected products include the following Zyxel firmware versions: vmg1312-b10a, vmg1312-b10b, vmg1312-b10e, vmg3312-b10a, vmg3313-b10a, vmg3926-b10b, vmg4325-b10a, vmg4380-b10a, vmg8324-b10a, vmg8924-b10a, sbg3300-n000, sbg3300-nb00, sbg3500-n000, and sbg3500-nb00.
Mitigation & Remediation
To mitigate the risks associated with CVE-2024-40891, organizations should apply the latest firmware updates provided by Zyxel. In addition, users should consider disabling Telnet access if it is not essential for operations.
For detailed guidance on application security measures, organizations should refer to resources such as the application security assessment best practices.
Detection Guidance
Organizations should monitor logs for any unusual Telnet activity and verify configurations for unauthorized command execution. Behavioral anomalies in network traffic may also indicate attempts to exploit this vulnerability.
AppSecure Threat Intelligence Insight
The emergence of CVE-2024-40891 highlights the ongoing challenges associated with legacy systems and the importance of regular firmware updates. Security teams should ensure their vulnerability management programs are robust enough to handle such risks effectively. For further insights, organizations can explore the vulnerability management program design and consider implementing penetration testing methodologies to proactively identify potential vulnerabilities.
Additionally, organizations should remain vigilant and stay informed about security advisories related to their vendors to ensure timely remediation.
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
.webp)