CVE-2024-11815 is a reflected cross-site scripting (XSS) vulnerability identified in the Pósturinn's Shipping with WooCommerce plugin for WordPress, affecting all versions up to and including 1.3.1. The vulnerability stems from improper neutralization of input during web page generation, specifically insufficient sanitization and escaping of the 'printed_marked' and 'nonprinted_marked' URL parameters. This flaw allows unauthenticated attackers to inject arbitrary JavaScript code into web pages generated by the plugin. When a victim user clicks a crafted malicious link containing these parameters, the injected script executes in their browser context. This can lead to theft of session cookies, defacement, or redirection to malicious sites, compromising confidentiality and integrity of user data. The vulnerability does not impact availability and requires user interaction but no authentication, increasing its exploitation potential. The reflected nature means the attack payload is delivered via a URL and executed immediately upon visiting or interacting with the link. No public exploits have been reported yet, but the plugin's widespread use in WooCommerce-based e-commerce sites makes this a notable risk. The CVSS 3.1 base score of 6.1 reflects a medium severity, with network attack vector, low attack complexity, no privileges required, user interaction required, and partial confidentiality and integrity impacts. The vulnerability is tracked under CWE-79 (Improper Neutralization of Input During Web Page Generation).

The primary impact of CVE-2024-11815 is on the confidentiality and integrity of user data within affected WordPress sites using the Pósturinn's Shipping with WooCommerce plugin. Successful exploitation can enable attackers to steal session cookies, perform actions on behalf of users, manipulate displayed content, or redirect users to malicious websites. This can lead to account compromise, phishing, or reputational damage for affected organizations. Since the vulnerability is reflected XSS, it requires user interaction, limiting automated mass exploitation but still posing significant risk via phishing campaigns or social engineering. The lack of authentication requirement broadens the attacker base. Availability is not impacted, so service disruption is unlikely. Organizations running e-commerce sites with this plugin may face increased risk of customer data exposure and trust erosion. The vulnerability could also be leveraged as a stepping stone for further attacks within the victim's session context.

1. Immediate upgrade to a patched version of the Pósturinn's Shipping with WooCommerce plugin once available from the vendor. Monitor vendor announcements for updates. 2. In the absence of a patch, implement web application firewall (WAF) rules to detect and block malicious payloads targeting the 'printed_marked' and 'nonprinted_marked' parameters. 3. Employ strict input validation and output encoding on these parameters at the application or reverse proxy level to neutralize script injection attempts. 4. Educate users and administrators about the risks of clicking on suspicious links, especially those containing unusual URL parameters related to shipping or order processing. 5. Conduct regular security audits and penetration testing focusing on plugin vulnerabilities and XSS vectors. 6. Consider disabling or replacing the vulnerable plugin if immediate patching is not feasible. 7. Enable Content Security Policy (CSP) headers to restrict execution of unauthorized scripts in browsers. 8. Monitor logs for unusual access patterns or repeated attempts to exploit these parameters. These targeted steps go beyond generic advice by focusing on the specific vulnerable parameters and plugin context.