CVE-2025-50019 is a medium-severity vulnerability classified under CWE-79, which refers to Improper Neutralization of Input During Web Page Generation, commonly known as Cross-site Scripting (XSS). This vulnerability affects the Simple Sticky Footer plugin developed by Sandor Kovacs, specifically versions up to and including 1.3.5. The flaw allows an attacker to inject malicious scripts that are stored persistently within the application, leading to Stored XSS. When a victim loads a page containing the malicious payload, the script executes in the context of the victim's browser, potentially compromising the confidentiality and integrity of user data. The CVSS 3.1 base score is 5.9, indicating a medium severity level. The vector string (CVSS:3.1/AV:N/AC:L/PR:H/UI:R/S:C/C:L/I:L/A:L) reveals that the attack is network exploitable (AV:N) with low attack complexity (AC:L), but requires high privileges (PR:H) and user interaction (UI:R). The scope is changed (S:C), meaning the vulnerability affects resources beyond the security scope of the vulnerable component. The impact on confidentiality, integrity, and availability is low to medium. No known exploits are currently reported in the wild, and no patches have been published yet. The vulnerability arises due to insufficient input sanitization or output encoding during web page generation, allowing malicious scripts to be stored and later executed in users' browsers. This can lead to session hijacking, defacement, or redirection to malicious sites, among other risks.

For European organizations using the Simple Sticky Footer plugin, this vulnerability poses a risk primarily to web applications that incorporate this plugin for footer management. Stored XSS can lead to unauthorized actions performed on behalf of authenticated users, theft of session cookies, or distribution of malware through the compromised website. The requirement for high privileges to exploit suggests that attackers need some level of authenticated access, which may limit exposure but does not eliminate risk, especially in environments with multiple users or where privilege escalation is possible. The changed scope indicates that the impact may extend beyond the immediate application, potentially affecting other integrated systems or user data. Organizations in sectors such as e-commerce, government, education, and media that rely on this plugin could face reputational damage, data breaches, or regulatory penalties under GDPR if user data confidentiality is compromised. The absence of known exploits in the wild provides a window for proactive mitigation but also means attackers may develop exploits in the future.

1. Immediate mitigation should involve restricting access to the plugin's administrative functions to trusted users only, minimizing the risk of malicious input submission. 2. Implement strict input validation and output encoding on all user-supplied data within the plugin, ensuring that any HTML or script content is properly sanitized before storage and rendering. 3. Monitor web application logs for unusual or suspicious input patterns that may indicate exploitation attempts. 4. Employ Content Security Policy (CSP) headers to limit the execution of unauthorized scripts in browsers, reducing the impact of potential XSS payloads. 5. Regularly update the plugin once a patch is released by the vendor or consider replacing the plugin with a more secure alternative if timely patches are not forthcoming. 6. Conduct security awareness training for administrators and users with high privileges to recognize and avoid actions that could facilitate exploitation. 7. Use web application firewalls (WAFs) configured to detect and block XSS attack patterns targeting this plugin. 8. Perform thorough security testing, including automated scanning and manual code review, focusing on input handling in the affected plugin.