CVE-2022-31040 is a medium-severity vulnerability classified under CWE-601, which involves an open redirect flaw in the Open Forms application, a tool used for creating and publishing smart forms. Specifically, the vulnerability exists in the cookie consent page of Open Forms versions prior to 1.0.9 and between 1.1.0-rc0 and before 1.1.1. The issue arises because the application accepts a 'referer' query string parameter without proper validation, allowing an attacker to inject a URL that redirects users to an untrusted external site. This redirection is initiated by the legitimate Open Forms backend page, which can deceive users into trusting the redirect, thereby increasing the risk of phishing attacks. The vulnerability does not require authentication or user interaction beyond clicking a crafted link, making exploitation relatively straightforward if users are tricked into visiting a malicious URL. The impact primarily affects the confidentiality and integrity of user interactions by potentially exposing users to phishing or malicious content. The vulnerability has been patched in versions 1.0.9 and 1.1.1 of Open Forms. No known exploits have been reported in the wild, and no workarounds are available, emphasizing the importance of timely patching. Given the nature of the vulnerability, it does not directly compromise system availability or allow remote code execution but poses a significant risk to end-user security through social engineering vectors.

For European organizations using Open Forms, this vulnerability could facilitate phishing campaigns that leverage the trusted domain of the Open Forms backend to redirect users to malicious sites. This can lead to credential theft, malware installation, or unauthorized data disclosure. Organizations in sectors with high user interaction through forms—such as government services, healthcare, finance, and e-commerce—are particularly at risk. The exploitation could undermine user trust in digital services and potentially lead to regulatory repercussions under GDPR if personal data is compromised. Since the vulnerability exploits user trust in legitimate URLs, it can be used to bypass some traditional email or web filtering defenses. The impact is thus more on the confidentiality and integrity of user data and communications rather than on system availability or backend infrastructure. The lack of known exploits suggests limited active targeting, but the ease of exploitation means that opportunistic attackers could leverage this vulnerability in phishing campaigns targeting European users.

The primary mitigation is to upgrade Open Forms installations to version 1.0.9 or 1.1.1 or later, where the vulnerability has been patched. Organizations should prioritize patch management for affected systems. Additionally, administrators should audit all URLs generated by Open Forms to ensure no unvalidated redirects remain. Implementing strict input validation and output encoding on query parameters, especially those controlling redirects, is essential. Web Application Firewalls (WAFs) can be configured to detect and block suspicious redirect patterns involving the 'referer' parameter. User awareness training should emphasize caution when clicking on links, even those appearing to come from trusted domains. Monitoring logs for unusual redirect requests can help detect exploitation attempts. Finally, organizations should consider implementing Content Security Policy (CSP) headers to restrict navigation to trusted domains, reducing the risk of redirection-based phishing.