Apache Httpd 2.4.18 Exploit May 2026
In Apache 2.4.18 with the mod_prefork MPM (Multi-Processing Module), the scoreboard shared memory segment is often created with world-writable permissions. Because the Apache child processes drop privileges to www-data, but the parent runs as root, a race condition or direct write to shm can lead to root execution.
For modern penetration testers, manual exploitation of 2.4.18 is inefficient. Tooling support includes:
A typical Nmap scan to confirm presence:
nmap -sV --script=http-request-smuggling.nse -p 80,443 target.com
There is no single exploit.exe for Apache 2.4.18—rather, the version serves as a repository of bypass and escalation techniques. The most critical takeaway is that version 2.4.18 is a proxy for organizational neglect. Modern exploits against it are rarely zero-days; they are reliable, well-documented chaining attacks (CVE-2016-4979 -> LPE -> root) available in standard penetration testing frameworks.
If a scan reveals Apache 2.4.18 in your perimeter, treat it not as a bug report but as an emergency. Every day that server remains unpatched, it acts as a turning key for request smuggling, cache poisoning, and eventual root compromise.
Disclaimer: This article is for educational and defensive cybersecurity purposes only. Exploiting systems without explicit written permission is illegal under the Computer Fraud and Abuse Act (CFAA) and similar laws worldwide.
Apache HTTP Server version 2.4.18 has several documented vulnerabilities, with the most notable being a local root privilege escalation. For a comprehensive list of all known issues for this specific release, you can consult the Apache HTTP Server 2.4 vulnerabilities official security page.
Primary Exploit: Local Root Privilege Escalation (CVE-2019-0211)
This is the most critical vulnerability affecting version 2.4.18. It allows a user with limited privileges (such as a script running under the web server) to gain root access on the host system. National Institute of Standards and Technology (.gov) apache httpd 2.4.18 exploit
: The exploit manipulates the "scoreboard"—a shared memory structure Apache uses to track worker processes. By writing a fake structure into shared memory, an attacker can hijack a function call during a "graceful restart".
: The vulnerability is usually triggered by a daily automated task like , which executes apache2ctl graceful Affected Modules mod_prefork mod_worker on Unix-based systems. Exploit Guide
: Detailed technical walkthroughs and proof-of-concept code are available at Exploit-DB (EDB-ID: 46676) Exploit-DB Secondary Vulnerabilities Other risks associated with this version include: X.509 Authentication Bypass (CVE-2016-4979) : Affects the experimental HTTP/2 module (
). It can allow unauthenticated remote attackers to bypass resource access controls. Path Normalization (CVE-2019-0220)
: Requests with multiple consecutive slashes in the URL can bypass certain security directives like LocationMatch RewriteRule if they aren't configured to handle duplicates. Optionsbleed (CVE-2017-9798)
: A memory leak vulnerability that can occur when processing files with certain
directives, potentially disclosing sensitive data from the server's memory. Apache HTTP Server Remediation To secure your server: Update Apache
: The most effective fix is to upgrade to the latest stable release (e.g., Harden Configuration : Follow the Apache Security Tips Hardening Guide to disable unnecessary modules like or experimental features that increase the attack surface. Apache HTTP Server In Apache 2
The Apache HTTP Server version 2.4.18 is notable in the security community primarily due to several high-profile vulnerabilities related to its implementation of the HTTP/2 (mod_http2) protocol and specific local privilege escalation flaws. Key Vulnerabilities & Exploit Reports HTTP/2 Denial of Service (CVE-2016-0150)
The Issue: Version 2.4.18 was one of the early adopters of the mod_http2 module. A flaw in how it handled request headers allowed attackers to cause a Denial of Service (DoS) by sending specially crafted HTTP/2 requests that would crash the server process.
Significance: This was a major "teething" issue for the then-new HTTP/2 protocol implementation in Apache, highlighting the risks of early adoption of complex network protocols. Local Privilege Escalation (CVE-2019-0211)
The Issue: Known as CARPE (Apache Root Privilege Escalation), this affects Apache versions 2.4.17 through 2.4.38. A less-privileged child process (like one running a PHP script) could manipulate the shared memory scoreboard to execute code as the root user during a graceful restart (apache2ctl graceful).
Exploit Potential: This is widely considered the most "interesting" exploit for this version range because it allows an attacker who has already compromised a website (via a CMS like WordPress) to take full control of the entire server. SSL/TLS Padding Oracle (CVE-2016-0701)
The Issue: While often tied to the underlying OpenSSL library, Apache 2.4.18 configurations were frequently targeted by "Padding Oracle" attacks. These allowed attackers to decrypt intercepted TLS traffic under specific conditions where the server leaked timing information. Summary Table: Vulnerability Impact Requirement CVE-2019-0211 Privilege Escalation Critical (Root Access) Local access / Compromised web script CVE-2016-0150 Denial of Service Remote (if HTTP/2 is enabled) CVE-2016-0736 Information Exposure Remote (related to mod_session_crypto) Why this version is "Interesting"
Version 2.4.18 sits at a crossroads of web history. It was released in late 2015/early 2016, a period when the web was transitioning to HTTP/2 and Always-on SSL. Most exploits for this version target these "new" features or the legacy way Apache manages its worker processes (the "Scoreboard").
Recommendation: If you are running 2.4.18, you are vulnerable to several critical exploits. It is highly recommended to update to at least version 2.4.39 or higher to mitigate the CARPE privilege escalation risk. A typical Nmap scan to confirm presence: nmap
Apache HTTP Server version 2.4.18 is affected by several vulnerabilities, with CVE-2016-0736 CVE-2019-0211
being among the most notable. Below is a guide on how these vulnerabilities function and how to secure your server. 1. Cryptographic Padding Oracle (CVE-2016-0736) This vulnerability exists in the mod_session_crypto
module. It allows a remote attacker to decrypt and modify session data stored in a user's browser. Exploit-DB
: The module failed to verify the integrity of encrypted session data before decryption. Because it used CBC (Cipher Block Chaining) mode without authenticated encryption, it was susceptible to a Padding Oracle Attack
: An attacker can gain unauthorized access by decrypting session cookies or forging new session data to impersonate users. Exploit Availability : Verified exploit scripts are available on platforms like Exploit-DB (EDB-ID: 40961) 2. Local Privilege Escalation (CVE-2019-0211) Often referred to as CARPE (DIEM)
, this flaw affects Apache 2.4.17 through 2.4.38 on Unix-based systems. Exploit-DB
: A vulnerability in how the "scoreboard" (shared memory used for worker communication) is handled. A low-privileged user (e.g.,
) who can execute code (via PHP or CGI) can manipulate the scoreboard. When the parent process performs a graceful restart, it can be tricked into executing arbitrary code with root privileges
: Full system compromise by escalating from a web user to the root user. Exploit Availability : A public proof-of-concept is available on Exploit-DB (EDB-ID: 46676) 3. HTTP Request Smuggling (CVE-2016-8743)
Apache 2.4.18 was overly "liberal" in how it handled whitespace in HTTP request headers. CVE Details Apache mod_session_crypto - Padding Oracle - Exploit-DB
