Apache Security Alert – RCE Vulnerability Fix Guide

Apache Security Alert (CVE-2026-23918) – Critical RCE Vulnerability Fix Guide

A critical vulnerability has been discovered in Apache HTTP Server that may allow attackers to execute remote code (RCE). The issue affects Apache’s HTTP/2 implementation and specifically impacts Apache 2.4.66.

Critical Severity: CVE-2026-23918 is a high-risk double-free memory corruption vulnerability with a CVSS score of 8.8. Servers exposed to the internet should be updated immediately.

What Is CVE-2026-23918?

CVE-2026-23918 is a double-free memory corruption vulnerability in Apache HTTP Server’s HTTP/2 module. The flaw is triggered during an early stream reset sequence and may allow attackers to manipulate memory structures and potentially achieve Remote Code Execution (RCE).

  • Remote Code Execution (RCE)
  • Memory corruption vulnerability
  • High exposure on public-facing servers
  • Critical impact on enterprise infrastructure

Affected Versions

  • Apache HTTP Server 2.4.66 ❌
  • Older versions may also be vulnerable
  • CloudLinux + cPanel EasyApache 4 servers may also be affected

Official Resolution

Apache released version 2.4.67 to patch CVE-2026-23918 and multiple additional security vulnerabilities. Updating to Apache 2.4.67 is currently the only complete fix.

CloudLinux / cPanel Servers

If your server uses CloudLinux with cPanel & WHM, the vulnerability may affect EasyApache 4 Apache packages as well. Administrators should update EasyApache packages immediately.

Recommended Action:
Update EasyApache 4 packages and verify Apache version after installation.

Update Apache (EasyApache 4)

CloudLinux / AlmaLinux

dnf clean all
dnf makecache
dnf -y update ea-apache*

RHEL-based Servers

yum clean all
yum makecache
yum -y update ea-apache*

Ubuntu Servers

apt update
apt install --only-upgrade "ea-apache24*"

Verify Installed Version

After updating Apache, verify the installed version: 

httpd -v

You should see:

Apache/2.4.67

Additional CVEs Fixed in Apache 2.4.67

The Apache 2.4.67 update also patches several additional vulnerabilities:

  • CVE-2026-24072
  • CVE-2026-28780
  • CVE-2026-29168
  • CVE-2026-29169
  • CVE-2026-33006
  • CVE-2026-33007
  • CVE-2026-33523
  • CVE-2026-33857
  • CVE-2026-34032
  • CVE-2026-34059

Mitigations (Temporary Protection)

Due to Apache HTTP Server’s widespread global usage, the RCE risk posed by CVE-2026-23918 represents a serious threat to production environments. If immediate patching is not possible, apply the following temporary mitigations:

🛡 Recommended Actions

  • Upgrade to Apache 2.4.67
    Only complete fix for all known vulnerabilities.
  • Disable HTTP/2 temporarily
    Reduces exposure to CVE-2026-23918 if immediate updating is not possible.
  • Remove mod_dav_lock if unused
    Helps mitigate CVE-2026-29169.
  • Audit .htaccess permissions
    Restrict local access to reduce privilege escalation risks related to CVE-2026-24072.
Warning: Temporary mitigations reduce exposure but do not fully resolve the vulnerability. Updating to Apache 2.4.67 should be considered mandatory.

Final Result After Updating

  • Critical RCE vulnerability patched
  • Apache HTTP/2 secured
  • Improved server stability and security
  • Protection against multiple additional CVEs
  • Safe EasyApache 4 environment for CloudLinux/cPanel servers

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Final Thoughts

CVE-2026-23918 is one of the most serious Apache HTTP Server vulnerabilities affecting HTTP/2 in recent years. System administrators should prioritize updating production systems immediately to reduce the risk of exploitation and infrastructure compromise.

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