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Home / Blog / Apache 2.4
Security Advisory

Apache 2.4: 212 CVEs Found – Critical Security Risks

📅 June 07, 2026 ·⏱ 5 min read ·🔒 SiteRecipe Security Team
1,711 websites still running Apache 2.4  → View full list
212
Total
41
Critical
82
High
86
Medium
2
Low

Apache HTTP Server 2.4 powers millions of websites worldwide, but recent security audits have uncovered a alarming number of vulnerabilities that demand immediate attention. Our analysis reveals 212 documented CVEs affecting this version, with 41 classified as critical severity—meaning attackers could potentially gain unauthorized access, bypass authentication, or execute malicious code on your server. If your website runs Apache 2.4, this comprehensive guide will help you understand the risks and take action to protect your online presence.

The severity of these vulnerabilities cannot be overstated. From authentication bypass exploits to remote code execution flaws, the threats range from data breaches to complete system compromise. With 1,711 websites still running vulnerable versions of Apache 2.4, the time to act is now. In this guide, we'll walk you through identifying whether your site is at risk and implementing the essential security patches that will keep your infrastructure safe.

What is Apache 2.4?

Apache HTTP Server (commonly called Apache) is the web server software that delivers web content from your server to visitors' browsers. Think of it as the digital postal worker—it receives requests for web pages and delivers them reliably. Apache 2.4 is a major version released to improve performance, security, and modern web standards support compared to earlier versions. Many businesses chose to deploy Apache 2.4 because it offered better handling of concurrent connections and improved SSL/TLS support for secure communications.

However, like all software, Apache 2.4 has undergone security patches throughout its lifecycle as researchers discovered vulnerabilities. These vulnerabilities are typically found in the core Apache code or in third-party libraries and modules that Apache uses to handle tasks like authentication, SSL encryption, and content type processing. When vulnerabilities are discovered but not patched, hackers can exploit them to compromise websites, steal data, or launch attacks against your visitors.

Key Vulnerabilities in Apache 2.4

212 CVEs found. The most critical are explained below.

CRITICAL CVE-2020-1953 10.0/10 · CVSS v3.1 ⏱ Immediate
Malicious YAML Files Can Execute Unauthorized Code

Apache Commons Configuration has a vulnerability where specially crafted YAML files can automatically run code on your server. If your website accepts or processes YAML files from users or external sources, attackers can abuse this to take control of your system.

Impact: An attacker could gain full control of your web server, steal customer data, modify website content, or use your server to attack other websites.

↗ View on NVD
CRITICAL CVE-2015-3253 9.8/10 · CVSS v3.0 ⏱ Immediate
Groovy Library Allows Remote Code Execution via Files

Apache Groovy (a programming tool) contains a flaw that lets attackers run malicious code through specially crafted files. If your website uses Groovy to process user-uploaded files or data, this vulnerability creates a serious security gap.

Impact: Attackers can execute arbitrary code on your server, potentially stealing sensitive data or completely compromising your website.

↗ View on NVD
CRITICAL CVE-2017-3167 9.8/10 · CVSS v3.1 ⏱ Immediate
Authentication Security Check Can Be Bypassed

A flaw in Apache httpd 2.4 allows third-party extensions to accidentally skip security checks that verify user login credentials. Users who shouldn't have access could potentially get through without proper authentication.

Impact: Unauthorized users could gain access to password-protected areas of your website without valid credentials, compromising user data and site security.

↗ View on NVD
CRITICAL CVE-2017-3169 9.8/10 · CVSS v3.0 ⏱ Within 7 days
HTTPS Connection Crash Due to Memory Error

Apache httpd 2.4 has a technical flaw where certain conditions can cause the HTTPS security layer to crash when processing requests. This happens due to third-party extensions interacting incorrectly with the HTTPS code.

Impact: Your website could experience crashes or become temporarily unavailable, disrupting service for customers and potentially exposing sensitive information.

↗ View on NVD
CRITICAL CVE-2017-7679 9.8/10 · CVSS v3.0 ⏱ Within 7 days
Memory Buffer Vulnerability in File Response Headers

Apache httpd 2.4 has a flaw where malicious response headers can cause the server to read data from memory incorrectly. An attacker can craft a special response to trigger this vulnerability.

Impact: An attacker could potentially read sensitive data from server memory or cause your website to crash.

↗ View on NVD
CRITICAL CVE-2012-0803 9.8/10 · CVSS v3.0 ⏱ Immediate
SOAP Security Token Validation Can Be Bypassed

Apache CXF (a web service tool) incorrectly validates security tokens in SOAP requests. An attacker can send an empty security token and bypass authentication checks designed to verify user identity.

Impact: Unauthorized users could bypass login requirements and gain access to protected services and data on your website.

↗ View on NVD

Additional Vulnerabilities (206 more)

Showing first 10 of 206. View all on NVD ↗

CVE IDSeverityScore PublishedDescription
CVE-2016-6814 CRITICAL 9.8 2018-01-18 When an application with unsupported Codehaus versions of Groovy from 1.7.0 to 2.4.3, Apache Groovy 2.4.4 to 2.4.7 on classpath uses standard Java serialization mechanisms, e.g. t…
CVE-2018-1312 CRITICAL 9.8 2018-03-26 In Apache httpd 2.2.0 to 2.4.29, when generating an HTTP Digest authentication challenge, the nonce sent to prevent reply attacks was not correctly generated using a pseudo-random…
CVE-2018-8018 CRITICAL 9.8 2018-07-20 In Apache Ignite before 2.4.8 and 2.5.x before 2.5.3, the serialization mechanism does not have a list of classes allowed for serialization/deserialization, which makes it possibl…
CVE-2020-9480 CRITICAL 9.8 2020-06-23 In Apache Spark 2.4.5 and earlier, a standalone resource manager's master may be configured to require authentication (spark.authenticate) via a shared secret. When enabled, howev…
CVE-2020-11984 CRITICAL 9.8 2020-08-07 Apache HTTP server 2.4.32 to 2.4.44 mod_proxy_uwsgi info disclosure and possible RCE
CVE-2021-26691 CRITICAL 9.8 2021-06-10 In Apache HTTP Server versions 2.4.0 to 2.4.46 a specially crafted SessionHeader sent by an origin server could cause a heap overflow
CVE-2021-30690 CRITICAL 9.8 2021-09-08 Multiple issues in apache were addressed by updating apache to version 2.4.46. This issue is fixed in Security Update 2021-004 Mojave. Multiple issues in apache.
CVE-2021-39275 CRITICAL 9.8 2021-09-16 ap_escape_quotes() may write beyond the end of a buffer when given malicious input. No included modules pass untrusted data to these functions, but third-party / external modules …
CVE-2021-41773 CRITICAL 9.8 2021-10-05 A flaw was found in a change made to path normalization in Apache HTTP Server 2.4.49. An attacker could use a path traversal attack to map URLs to files outside the directories co…
CVE-2021-42013 CRITICAL 9.8 2021-10-07 It was found that the fix for CVE-2021-41773 in Apache HTTP Server 2.4.50 was insufficient. An attacker could use a path traversal attack to map URLs to files outside the director…
Full Report Available

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How to Fix These Vulnerabilities

Conclusion

The discovery of 212 CVEs in Apache 2.4—including 41 critical vulnerabilities—represents a significant security risk for the 1,711 websites still running unpatched versions. These aren't theoretical threats; attackers actively exploit known vulnerabilities like CVE-2017-3167 (authentication bypass) and CVE-2017-3169 (NULL pointer dereference) to gain unauthorized access to web servers. Delaying your security updates increases the likelihood that your website will become a target, potentially exposing customer data, damaging your reputation, and violating compliance regulations.

Protecting your website requires more than just patching Apache—you need a comprehensive security strategy that includes regular vulnerability scanning, security monitoring, and proactive threat detection. SiteRecipe.com provides automated security scanning tools that identify vulnerabilities across your entire web infrastructure, track patch progress, and alert you immediately when new threats emerge. Don't wait for a breach to happen. Visit SiteRecipe.com today to scan your Apache servers, discover hidden vulnerabilities, and get step-by-step remediation guidance tailored to your specific environment.

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DISCLAIMER: This report is based on publicly available CVE data from the National Vulnerability Database (NVD) maintained by NIST. Detection of a technology version does not confirm active exploitation on any specific website. For informational purposes only. SiteRecipe is not responsible for actions taken based on this report. Always consult a qualified security professional.

Source: nvd.nist.gov · Published: June 07, 2026 · SiteRecipe.com