CVE-2020-23217 in phpList
Summary
by MITRE • 07/02/2021
A stored cross site scripting (XSS) vulnerability in phplist 3.5.3 allows attackers to execute arbitrary web scripts or HTML via a crafted payload entered into the "Add a list" field under the "Import Emails" module.
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Analysis
by VulDB Data Team • 07/09/2021
This stored cross site scripting vulnerability exists within phplist version 3.5.3 within the Import Emails module where the application fails to properly sanitize user input submitted through the "Add a list" field. The flaw allows an attacker to inject malicious scripts that persist in the application's database and execute whenever the affected page is rendered to users. This represents a classic stored XSS attack vector where the malicious payload is stored server-side rather than executed through a single request. The vulnerability stems from insufficient input validation and output encoding mechanisms that should have been implemented to prevent untrusted data from being executed as code within the browser context. According to CWE-79, this vulnerability directly maps to improper neutralization of input during web output, which is a fundamental weakness in web application security design. The attack requires minimal privileges as the vulnerability exists within a standard administrative function that typically requires authentication but does not adequately protect against malicious input injection.
The operational impact of this vulnerability extends beyond simple script execution as it can enable attackers to perform session hijacking, deface the application interface, steal sensitive user information, or redirect victims to malicious sites. An attacker who gains access to an administrative account could inject scripts that capture cookies, modify application behavior, or establish persistent backdoors within the system. The stored nature of the vulnerability means that once the malicious payload is submitted, it remains active until manually removed, potentially affecting all users who view the affected page. This vulnerability particularly impacts organizations relying on phplist for email campaign management, as it could compromise the integrity of their mailing lists and user data. The attack vector specifically targets the Import Emails functionality, which is commonly used by administrators to manage subscriber lists, making this a high-risk exposure point for email marketing systems.
Mitigation strategies should focus on implementing comprehensive input sanitization and output encoding controls throughout the application. The primary defense involves validating and sanitizing all user inputs before storage, particularly within administrative modules where privileged actions occur. Organizations should implement proper Content Security Policy headers to limit script execution capabilities and ensure that all user-supplied data is properly escaped when rendered in HTML contexts. The application should enforce strict input validation rules that reject potentially dangerous characters and patterns commonly associated with XSS attacks. Additionally, implementing a web application firewall capable of detecting and blocking suspicious payloads can provide an additional layer of protection. According to ATT&CK framework, this vulnerability maps to T1059.001 Command and Scripting Interpreter and T1566.001 Phishing, as attackers can leverage this vulnerability to establish persistent access and deliver malicious payloads to users. Regular security updates and patch management are essential as this vulnerability was likely addressed in subsequent versions of phplist through proper input sanitization and output encoding mechanisms. Organizations should also conduct regular security assessments of their web applications to identify similar input validation weaknesses that could expose their systems to similar stored XSS threats.