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How the CVE Works:
CVE-2021-41773 is a path traversal vulnerability in Apache HTTP Server 2.4.49. The flaw arises due to improper validation of file paths in URLs. An attacker can exploit this by sending crafted requests containing directory traversal sequences (e.g., /../). If mod_cgi is enabled, this allows unauthorized access to files outside the web root directory. In some cases, it can lead to remote code execution (RCE) if scripts are executed with insufficient input sanitization. The vulnerability stems from a normalization issue in the `ap_normalize_path()` function, which fails to block malicious sequences after URL encoding.
DailyCVE Form:
Platform: Apache HTTP Server
Version: 2.4.49
Vulnerability: Path Traversal
Severity: Critical
Date: 2021-10-05
Prediction: Patch expected by 2021-10-07
What Undercode Say:
curl -v "http://target.com/cgi-bin/.%2e/%2e%2e/%2e%2e/etc/passwd"
import requests url = "http://target.com/cgi-bin/.%2e/%2e%2e/%2e%2e/etc/passwd" response = requests.get(url) print(response.text)
How Exploit:
Craft HTTP requests with encoded traversal sequences (%2e%2e/) to access restricted files.
Protection from this CVE:
Update to Apache 2.4.50 or later. Disable mod_cgi if unused.
Impact:
Unauthorized file access, potential RCE.
Sources:
Reported By: www.cve.org
Extra Source Hub:
Undercode
