Apache Software has released an update patching critical remote code execution vulnerability in Apache HTTP Server.

A PoC (Proof of Concept) exploit has been published, and the vulnerability has been seen exploited in the wild.

The vulnerability

CVE-2021-41773 Path traversal vulnerability allowing RCE

A vulnerability 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 expected document root.

If files outside of the document root are not protected by “require all denied” these requests can succeed.

Additionally, this vulnerability could leak the source of interpreted files like CGI scripts.

The vulnerability turns into a Remote Code Execution (RCE) vulnerability on a Linux system if the server is configured to support CGI via mod_cgi.

This issue is known to be exploited in the wild.

Affected Versions

This issue only affects Apache 2.4.49 and not earlier versions.

Mitigation

CYREBRO urges all clients using Apache HTTP servers from the “Affected Versions” list to update the latest version 2.4.50

References: Apache.org