CVE-2025-23620 in Captchelfie Plugin
Summary
by MITRE • 01/16/2025
Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting') vulnerability in Alexey Trofimov Captchelfie – Captcha by Selfie allows Reflected XSS.This issue affects Captchelfie – Captcha by Selfie: from n/a through 1.0.7.
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Analysis
by VulDB Data Team • 02/10/2025
This vulnerability represents a classic reflected cross-site scripting flaw that undermines the security of web applications by allowing malicious actors to inject client-side scripts into web pages viewed by other users. The issue manifests within the Alexey Trofimov Captchelfie plugin, specifically targeting the captcha by selfie functionality that processes user input through web page generation mechanisms. The vulnerability occurs when the application fails to properly sanitize or escape user-supplied data before incorporating it into dynamically generated web content, creating an attack surface where malicious payloads can be executed in the context of other users' browsers.
The technical implementation of this reflected XSS vulnerability stems from inadequate input validation and output encoding practices within the plugin's codebase. When users interact with the selfie captcha functionality, their input data flows through the application's processing pipeline without sufficient sanitization measures. This allows attackers to craft malicious payloads that, when submitted through the captcha interface, get reflected back to the user's browser in the page response. The vulnerability affects all versions from the initial release through version 1.0.7, indicating a persistent flaw that has not been adequately addressed in the plugin's development lifecycle.
The operational impact of this vulnerability extends beyond simple script execution, as it provides attackers with the capability to perform session hijacking, deface web pages, steal sensitive cookies, or redirect users to malicious sites. Attackers can exploit this weakness by crafting specially formatted input that, when processed by the captcha system, gets embedded into the generated HTML response. The reflected nature of the vulnerability means that the malicious script executes in the victim's browser context, potentially allowing attackers to access session tokens, personal information, or perform unauthorized actions on behalf of users. This creates a significant risk for websites that rely on the plugin for user authentication and verification processes.
Mitigation strategies should focus on implementing comprehensive input validation and output encoding mechanisms throughout the plugin's codebase. The primary defense involves sanitizing all user inputs before they are processed or displayed in web pages, ensuring that any potentially malicious content is neutralized through proper escaping or encoding techniques. Additionally, developers should implement Content Security Policy headers to limit script execution and prevent unauthorized code injection. The vulnerability aligns with CWE-79, which specifically addresses cross-site scripting flaws, and maps to ATT&CK technique T1566.001 for initial access through spearphishing attachments and T1071.001 for application layer protocol usage. Regular security audits and code reviews should be implemented to identify similar input handling issues, while maintaining updated version control practices to ensure users deploy secure configurations.