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)
: 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
Understanding the Risks of Apache httpd 2.4.18 Apache httpd version 2.4.18, released in late 2015, remains common in legacy environments—most notably as the default version in Ubuntu 16.04 LTS (Xenial Xerus) apache httpd 2.4.18 exploit
. However, sticking with this version today poses significant security risks. If you are still running 2.4.18, you are exposed to several well-documented vulnerabilities that can lead to everything from information leaks to full server compromise. Key Vulnerabilities in Apache 2.4.18
While 2.4.18 was a stable release in its time, years of security research have uncovered critical flaws that affect it:
Trending CVEs for the Week of April 8th, 2019 - Blog - NopSec
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. Apache HTTP Server version 2
The Apache httpd 2.4.18 Exploit: A Web Server Nightmare
It was a typical Monday morning for John, a system administrator at a large financial institution. He was sipping his coffee and checking his email when he noticed a strange alert on his monitoring dashboard. The Apache httpd server, which hosted the company's website and several internal applications, was acting suspiciously.
As he dug deeper, John discovered that the server was running Apache httpd version 2.4.18, an outdated version that was vulnerable to a known exploit. The alert indicated that someone had been attempting to exploit the vulnerability, trying to gain unauthorized access to the server.
The vulnerability, known as CVE-2017-15715, was a critical issue in Apache httpd 2.4.18 that allowed an attacker to execute arbitrary code on the server. It was a bug in the mod_lua module, which allowed Lua scripts to be executed on the server.
John quickly realized that the attacker had already gained a foothold on the server. He saw that several suspicious Lua scripts had been uploaded to the server, and the attacker's IP address was logged in the server's access logs.
The attacker, who was using a VPN to mask their IP address, had been probing the server for several days, trying to find a way in. They had used a combination of Nmap and Nikto to scan the server and identify the vulnerability.
Once they had exploited the vulnerability, they had uploaded a malicious Lua script that allowed them to execute system commands on the server. The script was cleverly disguised as a legitimate configuration file, but John was able to spot it using his monitoring tools.
John immediately sprang into action, blocking the attacker's IP address and isolating the server from the rest of the network. He then began to investigate the extent of the damage, checking for any signs of data breaches or other malicious activity.
As he dug deeper, John discovered that the attacker had been trying to use the server as a pivot point to gain access to other internal systems. They had attempted to use the server to scan for other vulnerable hosts on the network, but John's security measures had prevented them from succeeding.
John spent the rest of the day cleaning up the server, removing the malicious scripts and patching the vulnerability. He also worked with his team to enhance the security measures on the server and the rest of the network, to prevent similar attacks in the future.
The incident had been a close call, but John's quick response had prevented a potentially disastrous breach. He made a mental note to stay on top of patching and vulnerability management, to prevent similar incidents from happening in the future. Mitigation and prevention:
Technical details:
Mitigation and prevention:
mod_lua module if not neededI can summarize known issues and exploitation details for Apache HTTPD 2.4.18 and point out mitigations. I'll assume you want a concise technical report-style summary — here it is.
To turn this into an exploit, a penetration tester would:
Expect header or timing analysis to fingerprint 2.4.18.mod_cache so all users receive a JavaScript payload.mod_security with CRS (Core Rule Set) v4+.lynis --cve-scan weekly.Severity: 7.5 (High)
Type: Memory Information Leak (leading to RCE in some cases)
The Vulnerability:
CVE-2017-9798, discovered by Hanno Böck, was a use-after-free vulnerability in mod_http2. When Apache 2.4.18 was compiled with HTTP/2 support (not default in 2.4.18, but common), an attacker could trigger a memory leak. The leak disclosed the contents of the server’s memory, potentially including htaccess directives, private keys, or session data.
Why this matters for exploits:
While not a direct RCE, memory leaks can bypass ASLR (Address Space Layout Randomization), making it easier to chain with other exploits. In 2017, researchers demonstrated that by triggering OptionsBleed repeatedly, one could reconstruct HTTP/2 connection memory.
Check for vulnerability:
nmap --script http-apache-negotiation -p 80 target.com
The Exploit Code:
Public PoCs exist (e.g., optionsbleed.py). However, the exploit is reliable only on non-default builds:
--enable-http2 (rare in LTS distros)Verdict: The closest to a high-impact exploit for 2.4.18, but limited by HTTP/2 activation.
Many threads about "apache httpd 2.4.18 exploit" are actually about bypassing Web Application Firewalls (WAFs) or ModSecurity rules on an Apache 2.4.18 backend. Attackers exploit:
For 2.4.18 specifically, request smuggling is less relevant because the patches for mod_proxy came later.