CVE-2021-42637 in Web Stack
Summary
by MITRE • 02/02/2022
PrinterLogic Web Stack versions 19.1.1.13 SP9 and below use user-controlled input to craft a URL, resulting in a Server Side Request Forgery (SSRF) vulnerability.
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Analysis
by VulDB Data Team • 07/06/2026
The PrinterLogic Web Stack vulnerability identified as CVE-2021-42637 represents a critical server side request forgery flaw that affects versions 19.1.1.13 and earlier releases. This vulnerability stems from the application's improper handling of user-controlled input during URL construction processes, creating an avenue for malicious actors to manipulate the application's behavior and potentially gain unauthorized access to internal systems. The flaw exists within the web stack's request processing mechanism where user-supplied data is directly incorporated into URL formation without adequate validation or sanitization measures. This type of vulnerability falls under the CWE-918 category, which specifically addresses server side request forgery conditions where applications use untrusted input to construct URLs for making requests to other systems. The vulnerability is particularly concerning because it allows remote attackers to make arbitrary requests from the affected server, potentially enabling them to access internal network resources, bypass firewalls, or perform unauthorized operations against backend services.
The technical exploitation of this SSRF vulnerability occurs when an attacker crafts malicious input that gets processed by the web application's URL construction logic. When the application receives user-controlled data and incorporates it directly into URL formation, the attacker can manipulate the target of the request to point to internal systems or services that should normally be inaccessible from the external network. This creates a pathway for attackers to perform reconnaissance activities, access internal databases, or even execute commands on systems that are typically protected by network segmentation. The vulnerability is classified under the ATT&CK technique T1071.004 which describes application layer protocol manipulation, specifically targeting web protocols where attackers can manipulate URL parameters to achieve unauthorized access. The flaw essentially allows attackers to use the PrinterLogic server as an intermediary to make requests to internal services, potentially leading to information disclosure, privilege escalation, or further lateral movement within the network infrastructure.
The operational impact of this vulnerability extends beyond simple data exposure, as it provides attackers with significant opportunities to compromise the entire network ecosystem. Organizations using affected PrinterLogic versions face potential risks including unauthorized access to internal resources, data exfiltration, and the ability to pivot to other systems within the network perimeter. The vulnerability affects the application's integrity and confidentiality by allowing unauthorized parties to manipulate the application's behavior and potentially gain access to sensitive internal systems. Attackers could exploit this weakness to enumerate internal network services, probe for vulnerable systems, or even attempt to establish persistent access through the compromised server. The implications are particularly severe for organizations that rely on PrinterLogic for print management and network services, as the compromised server could serve as a gateway for more extensive attacks. This vulnerability directly impacts the principle of least privilege by allowing external attackers to bypass normal access controls and potentially gain access to systems that should only be reachable through internal network connections. The affected environment's security posture becomes significantly weakened, as the vulnerability enables attackers to perform actions that would normally require insider access or direct network penetration.
Mitigation strategies for CVE-2021-42637 should prioritize immediate patching of affected PrinterLogic Web Stack versions to the latest releases that contain fixes for this SSRF vulnerability. Organizations should implement network segmentation controls to limit the potential impact of exploitation by restricting access to internal systems from the affected web application. Input validation and sanitization measures must be strengthened throughout the application's codebase to ensure that all user-controlled data is properly validated before being used in URL construction processes. Network-based controls such as web application firewalls and proxy configurations should be deployed to monitor and filter suspicious URL patterns that could indicate SSRF attempts. Regular security assessments and penetration testing should be conducted to identify similar vulnerabilities in other applications within the organization's infrastructure. The implementation of proper access controls and authentication mechanisms for internal services can help reduce the potential impact if exploitation occurs, while also ensuring that even if an attacker gains access through this vulnerability, they cannot easily move laterally through the network. Additionally, organizations should establish monitoring procedures to detect unusual network traffic patterns that might indicate exploitation attempts and maintain detailed audit logs of all URL construction activities within the affected applications.