Apache's Forbidden Dance: The Path Traversal Disaster of 2.4.49

Alon Barad

Software Engineer

Jan 7, 2026·6 min read·5 visits

Active ExploitationCISA KEV ListedRansomware Use

Executive Summary (TL;DR)

Apache 2.4.49 introduced a new path normalization function that forgot how URL encoding works. By replacing dots with `%2e`, attackers can walk out of the web root (`/var/www/html`) and into the server root (`/`). If `mod_cgi` is on, they can execute `/bin/sh` and take over the box. Patch immediately to 2.4.51 (skip 2.4.50, it was broken too).

A critical path traversal vulnerability in Apache HTTP Server 2.4.49 allows unauthenticated attackers to map URLs to files outside the expected document root. If CGI is enabled, this escalates to Remote Code Execution (RCE). The flaw stems from a botched path normalization logic change that failed to account for URL-encoded characters.

Official Patches

ApacheApache HTTP Server 2.4 vulnerabilities list

Fix Analysis (1)

Technical Appendix

CVSS Score

9.8/ 10

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

EPSS Probability

94.38%

Top 0% most exploited

100,000

Estimated exposed hosts via Shodan

Affected Systems

Apache HTTP Server 2.4.49

Affected Versions Detail

Product	Affected Versions	Fixed Version
Apache HTTP Server Apache Software Foundation	= 2.4.49	2.4.51

Attribute	Detail
CWE ID	CWE-22
Attack Vector	Network
CVSS	9.8 (Critical)
EPSS Score	94.38%
Impact	RCE & Information Disclosure
Exploit Status	Active / Weaponized
KEV Listed	Yes

MITRE ATT&CK Mapping

T1190Exploit Public-Facing Application

Initial Access

T1005Data from Local System

Collection

T1059.004Command and Scripting Interpreter: Unix Shell

Execution

CWE-22

Improper Limitation of a Pathname to a Restricted Directory ('Path Traversal')

The software uses external input to construct a pathname that is intended to identify a file or directory that is located underneath a restricted parent directory, but the software does not properly neutralize special elements within the pathname that can cause the pathname to resolve to a location that is outside of the restricted directory.