CVE-2026-2153 is an open redirect vulnerability identified in the mwielgoszewski doorman software, specifically affecting versions 0.1 through 0.6. The vulnerability resides in the is_safe_url function located in the doorman/users/views.py source file. This function is intended to validate URLs passed via the 'Next' parameter to prevent redirection to untrusted locations. However, due to insufficient validation logic, an attacker can manipulate the 'Next' argument to redirect users to arbitrary external URLs. This flaw can be exploited remotely without requiring any authentication, although it necessitates user interaction to trigger the redirect (e.g., clicking a crafted link). The vulnerability has a CVSS 4.0 score of 5.3, reflecting a medium severity based on its network attack vector, low complexity, no privileges required, and user interaction needed. The impact primarily affects user trust and security by enabling phishing and social engineering attacks that leverage the open redirect to disguise malicious destinations behind legitimate URLs. While no known exploits have been observed in the wild, the public disclosure of this vulnerability increases the likelihood of exploitation attempts. The absence of patches or official remediation links indicates that users must implement interim mitigations such as enhanced URL validation or disabling the vulnerable functionality. This vulnerability highlights the importance of rigorous input validation in web applications to prevent redirect-based attacks.

The primary impact of CVE-2026-2153 is the facilitation of phishing and social engineering attacks through malicious redirection. Attackers can exploit the open redirect to craft URLs that appear to originate from a trusted domain but redirect victims to harmful websites, potentially leading to credential theft, malware distribution, or further exploitation. Although the vulnerability does not directly compromise system confidentiality, integrity, or availability, it undermines user trust and can serve as a stepping stone for more severe attacks. Organizations relying on the affected doorman versions may face reputational damage and increased risk of successful phishing campaigns targeting their users. The medium severity rating reflects that exploitation is relatively straightforward and does not require authentication, but user interaction is necessary. The scope is limited to applications using the vulnerable versions of doorman, which may be niche or specialized, but any deployment in critical environments could amplify the consequences. Overall, the vulnerability poses a moderate risk that should be addressed promptly to prevent exploitation and protect end users.

To mitigate CVE-2026-2153, organizations should first check for and apply any available patches or updates from the mwielgoszewski doorman project once released. In the absence of official patches, developers should review and enhance the is_safe_url function to enforce strict validation of the 'Next' parameter, ensuring it only allows redirects to trusted internal URLs or whitelisted domains. Implementing a whitelist approach rather than relying on blacklists can significantly reduce the risk of open redirects. Additionally, consider encoding or sanitizing URL parameters to prevent manipulation. Organizations can also implement web application firewalls (WAFs) with rules designed to detect and block suspicious redirect patterns. User education about the risks of clicking unknown links and employing multi-factor authentication can help mitigate the impact of phishing attempts leveraging this vulnerability. Monitoring logs for unusual redirect activity and employing URL reputation services can provide early detection of exploitation attempts. Finally, consider disabling or restricting the use of the 'Next' parameter if it is not essential to application functionality.