CVE-2024-39573 is a vulnerability identified in the Apache HTTP Server, specifically affecting versions 2.4.59 and earlier. The root cause is improper input validation (CWE-20) within the mod_rewrite module, which is responsible for rewriting requested URLs based on configured rules. This flaw allows attackers to craft malicious RewriteRules that cause the server to redirect URLs to be processed by mod_proxy, enabling Server-Side Request Forgery (SSRF). SSRF vulnerabilities allow attackers to make the server perform unauthorized requests to internal or external systems, potentially exposing sensitive information or enabling further attacks within the internal network. The vulnerability does not require any privileges or user interaction, making it remotely exploitable over the network. The CVSS v3.1 score of 7.5 reflects a high severity, primarily due to the vulnerability's network attack vector, low complexity, and the high confidentiality impact, although integrity and availability are not affected. The Apache Software Foundation has addressed this issue in version 2.4.60, and users are strongly advised to upgrade. No public exploits or active exploitation campaigns have been reported yet, but the presence of this vulnerability in widely deployed web servers makes it a significant concern.

For European organizations, the impact of CVE-2024-39573 can be substantial. Apache HTTP Server is widely used across Europe in enterprise, government, and critical infrastructure environments. Successful exploitation could allow attackers to bypass perimeter defenses and access internal services that are otherwise inaccessible, leading to unauthorized data disclosure and potential reconnaissance for further attacks. Confidentiality breaches could affect sensitive personal data, intellectual property, or operational information, raising compliance and regulatory risks under GDPR. Although the vulnerability does not directly affect integrity or availability, the SSRF can be a stepping stone for more complex attacks, including lateral movement or exploitation of internal vulnerabilities. Organizations relying on legacy Apache versions or complex RewriteRule configurations are particularly vulnerable. The lack of required authentication and user interaction increases the likelihood of exploitation if unpatched.

1. Upgrade Apache HTTP Server to version 2.4.60 or later immediately to apply the official fix. 2. Conduct a thorough audit of all mod_rewrite configurations to identify and remove or secure any unsafe RewriteRules that could redirect requests to mod_proxy. 3. Implement strict network segmentation and firewall rules to limit the web server's ability to initiate outbound requests to internal services, reducing SSRF impact. 4. Monitor web server logs for unusual or unexpected proxy requests that could indicate exploitation attempts. 5. Employ web application firewalls (WAFs) with rules designed to detect and block SSRF patterns related to mod_rewrite misuse. 6. Regularly review and update security policies related to web server configurations and internal network access controls. 7. Educate system administrators and developers about the risks of SSRF and secure URL rewriting practices.