CVE-2021-4105 in COSLAT Firewall
Summary
by MITRE • 02/24/2023
Improper Handling of Parameters vulnerability in BG-TEK COSLAT Firewall allows Remote Code Inclusion.
This issue affects COSLAT Firewall: from 5.24.0.R.20180630 before 5.24.0.R.20210727.
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Analysis
by VulDB Data Team • 05/18/2026
The CVE-2021-4105 vulnerability represents a critical improper handling of parameters flaw within the BG-TEK COSLAT Firewall software ecosystem. This vulnerability manifests as a remote code inclusion risk that stems from inadequate validation and sanitization of user-supplied parameters within the firewall's processing pipeline. The affected version range spans from 5.24.0.R.20180630 through the vulnerable state preceding 5.24.0.R.20210727, indicating a substantial timeframe during which systems remained exposed to potential exploitation. The vulnerability's classification aligns with CWE-20, which specifically addresses improper input validation, making it a prime target for attackers seeking to compromise network security infrastructure.
The technical implementation of this flaw occurs when the COSLAT Firewall processes incoming network requests containing malformed or specially crafted parameters that bypass normal input validation mechanisms. Attackers can leverage this weakness by injecting malicious code through parameter manipulation, potentially gaining unauthorized access to the underlying system. The vulnerability operates at the application layer, specifically targeting the firewall's parameter parsing and handling functions that are responsible for processing configuration data, network traffic parameters, and administrative commands. This improper parameter handling creates an attack surface where remote adversaries can execute arbitrary code on the affected firewall system, effectively undermining the fundamental security posture that firewalls are designed to maintain.
The operational impact of CVE-2021-4105 extends far beyond simple network disruption, as it provides attackers with potential full system compromise capabilities. Organizations utilizing affected COSLAT Firewall versions face significant risk of unauthorized network access, data exfiltration, and potential lateral movement within their network infrastructure. The vulnerability's remote exploitability means that attackers do not require physical access or network proximity to the device, making it particularly dangerous in environments where firewalls serve as primary network security controls. From an attack perspective, this vulnerability maps to ATT&CK technique T1059.007 for command and scripting interpreter, as successful exploitation would likely involve executing malicious code through compromised firewall processes, potentially enabling persistent access and further network infiltration.
Security professionals should prioritize immediate remediation efforts by upgrading to the patched version 5.24.0.R.20210727 or later, as this represents the definitive fix for the parameter handling flaw. Organizations should also implement network segmentation and monitoring to detect anomalous traffic patterns that might indicate exploitation attempts. Additional mitigations include deploying network access controls to limit access to firewall management interfaces, implementing strict input validation on all network-facing applications, and conducting comprehensive vulnerability assessments of other network security appliances that may share similar parameter handling implementations. The vulnerability's presence in firewall infrastructure underscores the critical importance of maintaining up-to-date security patches and the necessity of robust security testing procedures to identify and remediate such fundamental flaws before they can be exploited by malicious actors.