CVE-2017-9841 in Communications Diameter Signaling Router
Summary
by MITRE
Util/PHP/eval-stdin.php in PHPUnit before 4.8.28 and 5.x before 5.6.3 allows remote attackers to execute arbitrary PHP code via HTTP POST data beginning with a "
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Analysis
by VulDB Data Team • 10/18/2025
The vulnerability identified as CVE-2017-9841 represents a critical remote code execution flaw within the PHPUnit testing framework that affected versions prior to 4.8.28 and 5.x before 5.6.3. This vulnerability resides in the Util/PHP/eval-stdin.php component of the framework and demonstrates a classic input validation and code execution weakness that has significant implications for web application security. The flaw specifically allows remote attackers to execute arbitrary PHP code through carefully crafted HTTP POST data that begins with a double quotation mark character, making it particularly dangerous as it can be exploited without requiring authentication or prior access to the system.
The technical mechanism behind this vulnerability involves improper handling of input data within the eval-stdin.php script, which processes PHP code submitted through HTTP POST requests. When a malicious user submits POST data starting with a double quote character, the framework fails to properly sanitize or validate this input before executing it within a PHP eval() context. This creates an execution path where attacker-controlled code can be interpreted and executed by the PHP interpreter, effectively granting remote attackers full control over the affected system. The vulnerability is categorized under CWE-94, which specifically addresses "Improper Control of Generation of Code ('Code Injection')" and aligns with the ATT&CK technique T1059.007 for "Command and Scripting Interpreter: Python" and similar execution methods that leverage code injection vulnerabilities.
The operational impact of CVE-2017-9841 extends far beyond simple code execution, as it provides attackers with complete system compromise capabilities that can lead to data theft, service disruption, and further lateral movement within networks. Since PHPUnit is commonly used in development environments and continuous integration pipelines, the vulnerability can be exploited in multiple contexts including development servers, testing environments, and even production systems where the framework is improperly configured or exposed. Organizations running vulnerable versions of PHPUnit face risks of unauthorized access to sensitive data, system manipulation, and potential use as a foothold for more extensive attacks. The vulnerability is particularly concerning because it can be exploited silently without generating obvious network traffic patterns, making detection and forensic analysis more challenging for security teams.
Mitigation strategies for CVE-2017-9841 focus primarily on immediate version updates to PHPUnit 4.8.28 or 5.6.3 and later releases, which contain patches that properly validate input data before processing. Organizations should also implement network segmentation to limit access to development environments where PHPUnit is installed, and consider disabling unnecessary HTTP endpoints that might expose the vulnerable eval-stdin.php script. Additional protective measures include implementing web application firewalls to detect and block suspicious POST data patterns, conducting regular security assessments of development environments, and ensuring proper input validation and sanitization throughout all application components. The vulnerability serves as a reminder of the importance of keeping development tools and frameworks updated, as well as the critical need for proper security configuration in non-production environments that may be accessible from external networks. Organizations should also consider implementing automated vulnerability scanning tools that can identify outdated framework versions and other security misconfigurations that could lead to similar exploitation vectors.