A critical remote code execution vulnerability has been discovered in Apache HTTP Server (httpd), affecting versions 2.4.48 through 2.4.59, allowing unauthenticated attackers to execute arbitrary code on affected systems.
The vulnerability was discovered by security researchers and independently verified by the Apache Foundation's security team. An exploit PoC has already been published, making immediate patching essential for all Apache deployments.
Technical Details:
Affected Versions: Apache httpd 2.4.48 to 2.4.59
CVE ID: CVE-2026-31337 (CVSS 9.8 - Critical)
Attack Vector: A specially crafted HTTP request containing malicious headers can bypass input validation in the mod_proxy module, leading to memory corruption and RCE.
Attack Complexity: Low - No authentication required; attack can be delivered over the network.
Immediate Actions Required:
1. Update Apache immediately to version 2.4.60 or later
2. Review web server logs for unusual header patterns or mod_proxy activity
3. Implement WAF rules blocking requests with suspicious header combinations
4. Disable mod_proxy if not required for your application
5. Monitor for signs of compromise including unusual process creation
Workarounds:
If immediate patching is not possible, temporarily disabling mod_proxy or restricting access to the server through firewall rules can reduce exposure. However, these are temporary measuresâpatching should be your priority.
Apache Foundation advises all administrators to treat this as a critical issue and prioritize patching across their infrastructure.