CVE-2020-10797 in pfSense
Summary
by MITRE
An XSS vulnerability resides in the hostname field of the diag_ping.php page in pfsense before 2.4.5 version. After passing inputs to the command and executing this command, the $result variable is not sanitized before it is printed.
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Analysis
by VulDB Data Team • 05/06/2025
The vulnerability identified as CVE-2020-10797 represents a cross-site scripting flaw within the pfSense firewall management interface, specifically affecting versions prior to 2.4.5. This issue manifests in the diag_ping.php page where the hostname field processing creates an avenue for malicious input execution. The vulnerability stems from inadequate input validation and output sanitization mechanisms within the web application's command execution flow. When users input data into the hostname field, the system processes this input through command execution routines without proper sanitization of the resulting output before rendering it back to the user interface. This design flaw directly enables attackers to inject malicious scripts that execute within the context of other users' browsers, exploiting the trust relationship between the web application and its users. The vulnerability operates at the intersection of input validation failures and output encoding issues, creating a pathway for persistent script injection attacks.
The technical implementation of this vulnerability follows a classic command injection pattern where user-supplied data flows from the web interface through command execution layers to the final output rendering. The $result variable contains the output from executed commands, but this data undergoes insufficient sanitization before being displayed to users. This creates an environment where malicious payloads can be embedded within the hostname field input and subsequently executed when the command results are rendered back to the browser. The flaw demonstrates poor security practices in data handling and output escaping, where the application fails to properly encode or escape special characters that could be interpreted as HTML or JavaScript code. This vulnerability aligns with CWE-79, which specifically addresses cross-site scripting flaws, and represents a failure in proper input sanitization and output encoding practices. The attack vector is particularly concerning as it leverages legitimate administrative functionality to deliver malicious payloads, making detection more challenging.
The operational impact of CVE-2020-10797 extends beyond simple script execution, as it enables attackers to potentially hijack user sessions, steal sensitive information, or perform unauthorized actions within the pfSense administrative interface. An attacker could craft malicious hostnames that, when processed by the ping command, would result in script execution that could exfiltrate data, modify firewall rules, or establish persistent access to the network infrastructure. The vulnerability affects the integrity and confidentiality of the firewall management system, potentially compromising the entire network security posture. Given that pfSense is widely deployed in enterprise and organizational environments, this vulnerability could provide attackers with a foothold to escalate privileges and gain deeper access to network resources. The impact is amplified by the fact that the vulnerability exists in the diagnostic utilities that administrators frequently use, making it more likely to be exploited in real-world scenarios.
Mitigation strategies for CVE-2020-10797 should prioritize immediate version upgrades to pfSense 2.4.5 or later, which contain the necessary patches to address the input sanitization and output encoding deficiencies. Organizations should implement comprehensive input validation mechanisms that sanitize all user-supplied data before processing, particularly within command execution contexts. The implementation of proper output encoding techniques, including HTML entity encoding and JavaScript context escaping, should be enforced throughout the application to prevent script injection. Network segmentation and access controls should be strengthened to limit exposure of the pfSense interface to trusted users only, while implementing web application firewalls to detect and block malicious payloads. Security monitoring should include detection of unusual ping command usage patterns and anomalous data flows that might indicate exploitation attempts. The vulnerability highlights the importance of following secure coding practices and implementing defense-in-depth strategies to protect critical network infrastructure components from sophisticated attacks. Regular security assessments and vulnerability scanning should be conducted to identify similar issues within other components of the network security infrastructure, ensuring comprehensive protection against evolving threat landscapes.