^{CVE-2023-27522:}HTTP Response Smuggling vulnerability in Apache HTTP Server via mod_proxy_uwsgi allows attackers to manipulate responses.

Overview

This vulnerability affects Apache HTTP Server versions 2.4.30 through 2.4.55 when the mod_proxy_uwsgi module is in use. HTTP Response Smuggling occurs when an attacker can manipulate HTTP responses by exploiting differences in how servers and clients interpret HTTP messages. In this case, special characters in origin response headers can cause the response to be improperly processed, creating opportunities for attackers to inject malicious content or extract sensitive information. The vulnerability could potentially lead to cache poisoning attacks, where an attacker poisons a web cache with malicious content that is then served to other users, or information leakage where responses intended for one user are exposed to another.

Remediation

1. Update Apache HTTP Server to version 2.4.56 or later, which contains fixes for this vulnerability.
2. If immediate updating is not possible, consider implementing one of the following mitigations:
   • Disable mod_proxy_uwsgi if it's not essential for your operations
   • Configure a security filter or WAF to inspect and validate HTTP responses
   • Implement strict Content-Security-Policy headers to minimize the impact of potential attacks
3. Monitor server logs for unusual HTTP response patterns that might indicate exploitation attempts
4. Review and test your application for proper handling of HTTP responses, especially when proxying to uwsgi backends

References

1. Apache HTTP Server Security Vulnerabilities: https://httpd.apache.org/security/vulnerabilities_24.html
2. Debian Security Advisory: https://lists.debian.org/debian-lts-announce/2023/04/msg00028.html
3. Gentoo Linux Security Advisory: https://security.gentoo.org/glsa/202309-01
4. MITRE CVE Entry: https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2023-27522
5. National Vulnerability Database: https://nvd.nist.gov/vuln/detail/CVE-2023-27522