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critical9.8Known exploitedPublic exploit code

CVE-2021-41773

Apache HTTP Server Path Traversal Vulnerability

Exploited in the wild

This vulnerability is on a Known Exploited Vulnerabilities catalogue, added 2021-11-03. Federal due date: 2021-11-17.

Apply updates per vendor instructions.

Public exploit code

Working exploit or proof of concept code has been published for this vulnerability. Treat unpatched systems as at risk.

Impact

A flaw 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 directories configured by Alias-like directives. If files outside of these directories are not protected by the usual default configuration "require all denied", these requests can succeed. If CGI scripts are also enabled for these aliased pathes, this could allow for remote code execution. This issue is known to be exploited in the wild. This issue only affects Apache 2.4.49 and not earlier versions. The fix in Apache HTTP Server 2.4.50 was found to be incomplete, see CVE-2021-42013.

Affected products

VendorProductAffected versions
ApacheHttp Server
Version 2.4.49
FedoraprojectFedora
Versions 34, 35
OracleInstantis Enterprisetrack
Versions 17.1, 17.2, 17.3
NetappCloud Backup
All versions

Weakness classification

References