CVE-2025-29003 in Holiday Calendar Plugin
Summary
by MITRE • 06/06/2025
Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting') vulnerability in mva7 The Holiday Calendar allows Stored XSS. This issue affects The Holiday Calendar: from n/a through 1.18.2.1.
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Analysis
by VulDB Data Team • 06/06/2025
This vulnerability represents a critical cross-site scripting flaw that enables attackers to inject malicious scripts into web pages viewed by other users. The issue manifests in the Holiday Calendar application where user input is not properly sanitized during web page generation, creating persistent XSS vectors. The vulnerability affects all versions from the initial release through 1.18.2.1, indicating a long-standing security weakness that has not been adequately addressed. The stored nature of this XSS vulnerability means that malicious scripts are permanently saved and executed whenever affected pages are loaded, making it particularly dangerous for web applications that process user-generated content.
The technical implementation of this vulnerability stems from inadequate input validation and output encoding mechanisms within the application's web page generation process. When users submit data through forms or other input methods, the application fails to properly neutralize potentially malicious content before storing it in the database or rendering it on web pages. This allows attackers to inject script tags, javascript code, or other malicious payloads that execute in the context of other users' browsers. The vulnerability specifically affects the Holiday Calendar application's handling of user input during the generation of web pages, creating a persistent threat vector that can compromise user sessions, steal sensitive information, or redirect users to malicious sites.
The operational impact of this stored XSS vulnerability is severe and multifaceted, potentially affecting thousands of users who interact with the Holiday Calendar application. Attackers can exploit this vulnerability to hijack user sessions, steal cookies and authentication tokens, perform unauthorized actions on behalf of users, and gain access to sensitive calendar data. The persistent nature of stored XSS means that the malicious code remains active until manually removed from the database, providing attackers with extended periods of access and control. This vulnerability can also be leveraged to deface web pages, redirect users to phishing sites, or establish command and control channels for further attacks on the organization's network infrastructure.
Organizations should immediately implement multiple layers of defense to mitigate this vulnerability, starting with urgent patching of all affected versions. The recommended approach includes implementing comprehensive input validation that filters or escapes all user-supplied data before storage or rendering, combined with proper output encoding that ensures malicious content cannot be executed in web browsers. Security headers such as Content Security Policy should be implemented to limit the execution of unauthorized scripts, while regular security audits should be conducted to identify similar vulnerabilities in other application components. Additionally, user input should be sanitized using established libraries and frameworks that properly handle potentially dangerous characters and script tags. The vulnerability aligns with CWE-79 which specifically addresses cross-site scripting flaws, and may be exploited through techniques described in the ATT&CK framework under T1566 for credential access and T1059 for command and control. Organizations should also consider implementing web application firewalls to detect and block suspicious input patterns while maintaining detailed logging of user activities for forensic analysis and threat hunting purposes.