Apache Httpd 2.4.18 Exploit May 2026

If you discover Apache 2.4.18 in your environment:

Configuration Hardening (if upgrade impossible):

WAF Rules: Deploy a WAF rule that rejects any request containing both Content-Length and Transfer-Encoding headers.

git clone https://github.com/hannob/optionsbleed
python3 optionsbleed.py http://victim

You will find that unless tweaked, most exploits yield limited results. This is the reality of Apache security post-2018.

If the target server was compiled with mod_http2 (not always enabled by default in 2.4.18), a separate critical vulnerability exists (CVE-2016-1546). This is a memory corruption issue in the HTTP/2 ping handler. apache httpd 2.4.18 exploit

To turn this into an exploit, a penetration tester would:

FROM ubuntu:16.04
RUN apt-get update && apt-get install -y apache2=2.4.18-2ubuntu3
# Enable mod_cgi, mod_http2, and set AllowOverride All
COPY vulnerable.cgi /usr/lib/cgi-bin/
CMD ["/usr/sbin/apache2ctl", "-D", "FOREGROUND"]

Apache HTTP Server 2.4.18 was released on December 13, 2015. As a version over a decade old, it is considered end-of-life (EOL) and no longer receives security backports from the Apache Software Foundation. While no single “universal remote code execution (RCE)” exploit exists exclusively for 2.4.18, the version is vulnerable to a chain of publicly disclosed high-severity vulnerabilities (CVE-2016-5387, CVE-2016-8743, CVE-2017-9798, CVE-2017-15710). Adversaries actively target systems running this version due to its prevalence in legacy IoT devices, outdated LAMP stacks, and unmaintained web hosting environments. If you discover Apache 2

Key Finding: Systems running Apache 2.4.18 should be considered compromised if exposed to the internet without a Web Application Firewall (WAF) or OS-level ACLs.

For educational purposes, an ethical hacker targeting a lab environment with Apache 2.4.18 would follow this roadmap: Configuration Hardening (if upgrade impossible):

Apache 2.4.18 fails to correctly reject malformed requests containing both a Content-Length header and a Transfer-Encoding: chunked header with ambiguous values. When placed behind a reverse proxy (e.g., Nginx, HAProxy), a malicious client can "split" a single request into two.

How the exploit works: