CVE-2025-31687 in SpamSpan filter
Summary
by MITRE • 04/01/2025
Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting') vulnerability in Drupal SpamSpan filter allows Cross-Site Scripting (XSS).This issue affects SpamSpan filter: from 0.0.0 before 3.2.1.
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Analysis
by VulDB Data Team • 08/28/2025
The vulnerability identified as CVE-2025-31687 represents a critical cross-site scripting flaw within the Drupal SpamSpan filter module, classified under CWE-79 - Improper Neutralization of Input During Web Page Generation. This vulnerability specifically impacts the web application's ability to properly sanitize user input during the generation of web pages, creating an avenue for malicious actors to inject and execute arbitrary JavaScript code within the context of a victim's browser session. The SpamSpan filter is designed to protect websites from spam by obfuscating email addresses, but the implementation contains a fundamental flaw in input validation that undermines this security measure.
The technical nature of this vulnerability stems from inadequate sanitization of user-provided data within the SpamSpan filter functionality. When the module processes input containing potentially malicious scripts, it fails to properly escape or remove dangerous characters that could be interpreted as executable code by web browsers. This improper neutralization occurs during the web page generation phase, where the filter should be sanitizing content but instead allows malicious payloads to persist and execute. The vulnerability affects all versions of the SpamSpan filter from version 0.0.0 up to and including version 3.2.0, creating a substantial attack surface across numerous Drupal installations that rely on this module for spam protection.
The operational impact of this vulnerability is severe and multifaceted, as it enables attackers to execute arbitrary JavaScript code in the context of any user who views affected web pages. This allows for session hijacking, credential theft, redirection to malicious sites, and potential data exfiltration from authenticated users. The attack vector is particularly concerning because it can be exploited through user input fields or content that gets processed by the SpamSpan filter, making it accessible to attackers who can influence content creation or modification. The vulnerability operates at the application layer and aligns with ATT&CK technique T1059.007 - Command and Scripting Interpreter: JavaScript, as it enables the execution of malicious javascript payloads.
Organizations affected by this vulnerability should immediately implement mitigations including updating to version 3.2.1 or later of the SpamSpan filter module, which contains the necessary patches to address the input sanitization issues. Additionally, administrators should review all content processed through the SpamSpan filter and implement additional input validation measures at the application level. The remediation process should include comprehensive testing to ensure that the patched version properly handles all forms of user input while maintaining the module's intended functionality for spam protection. Security monitoring should be enhanced to detect any suspicious script injection attempts, and regular vulnerability assessments should be conducted to identify similar issues in other components of the Drupal ecosystem. This vulnerability underscores the critical importance of proper input sanitization and the potential consequences of inadequate security controls in web application development practices.