CVE-2024-6844 identifies a vulnerability in the corydolphin/flask-cors Python library, version 4.0.1 and potentially others, related to improper origin validation due to inconsistent handling of the '+' character in URL paths. The root cause lies in the use of the unquote_plus function on the request.path, which converts '+' characters into spaces (' '). This transformation leads to incorrect normalization of URL paths, causing the CORS middleware to mismatch the request path against configured CORS rules. Consequently, endpoints may either fail to enforce the intended CORS policies or inadvertently allow unauthorized cross-origin requests. This vulnerability is categorized under CWE-346 (Origin Validation Error), which typically involves improper validation of the origin or referer headers in web applications. The CVSS v3.0 base score is 5.3 (medium), reflecting that the vulnerability can be exploited remotely without authentication or user interaction, with limited impact on confidentiality and no impact on integrity or availability. No public exploits are currently known. The flaw can cause security risks by permitting unauthorized cross-origin resource sharing, potentially exposing sensitive data or functionality to malicious web origins. Additionally, legitimate cross-origin requests may be blocked, causing usability issues. The vulnerability affects web applications using flask-cors for CORS policy enforcement, a common Python library for Flask-based applications. Since the affected versions are unspecified, users should assume all versions prior to a fix are vulnerable. The lack of patch links indicates a fix may not yet be publicly available, so mitigation may require workarounds or careful configuration review.

For European organizations, the impact of CVE-2024-6844 can be significant, especially for those deploying Flask-based web applications that rely on flask-cors for enforcing CORS policies. Unauthorized cross-origin access could lead to data leakage or unauthorized actions performed via cross-site requests, undermining confidentiality. While the vulnerability does not affect integrity or availability directly, the exposure of sensitive endpoints to untrusted origins can facilitate further attacks or data exfiltration. Additionally, legitimate users may experience service disruptions if valid cross-origin requests are blocked due to misapplied CORS rules, affecting user experience and business operations. Organizations in sectors with strict data protection requirements, such as finance, healthcare, and government services, could face compliance risks if sensitive data is exposed. The medium CVSS score reflects a moderate risk, but the ease of exploitation (no authentication or user interaction required) means attackers can potentially exploit this vulnerability at scale. European companies using flask-cors in public-facing APIs or internal applications accessible via browsers should prioritize assessment and remediation to prevent exploitation.

To mitigate CVE-2024-6844, European organizations should take the following specific actions: 1) Immediately audit all Flask applications using flask-cors to identify affected versions and usage patterns. 2) Review CORS configurations to ensure strict origin validation and avoid relying solely on path-based matching that could be affected by URL normalization issues. 3) Implement custom CORS validation logic that correctly handles '+' characters in URL paths without using unquote_plus or similar functions that alter the path semantics. 4) Monitor official flask-cors repositories and security advisories for patches or updates addressing this vulnerability and apply them promptly once available. 5) Consider deploying Web Application Firewalls (WAFs) with rules to detect and block suspicious cross-origin requests that do not conform to expected patterns. 6) Conduct penetration testing focused on CORS misconfigurations to identify potential unauthorized access vectors. 7) Educate developers about the risks of improper URL normalization in security-critical components like CORS enforcement. 8) If immediate patching is not possible, restrict CORS policies to trusted origins only and minimize the attack surface by disabling CORS where not strictly necessary.