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AUSCERT External Security Bulletin Redistribution
CVE-2021-42013: Path Traversal and Remote Code Execution in Apache HTTP
Server 2.4.49 and 2.4.50 (incomplete fix of CVE-2021-41773)
8 October 2021
AusCERT Security Bulletin Summary
Product: Apache HTTP Server
Publisher: Apache Software Foundation
Operating System: UNIX variants (UNIX, Linux, OSX)
Impact/Access: Execute Arbitrary Code/Commands -- Remote/Unauthenticated
Access Privileged Data -- Remote/Unauthenticated
Reduced Security -- Remote/Unauthenticated
CVE Names: CVE-2021-42013 CVE-2021-41773
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critical: Path Traversal and Remote Code Execution in Apache HTTP Server 2.4.49
and 2.4.50 (incomplete fix of CVE-2021-41773) (CVE-2021-42013)
It was found that the fix for CVE-2021-41773 in Apache HTTP Server 2.4.50 was
insufficient. 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 only affects Apache 2.4.49 and Apache 2.4.50 and not earlier versions.
Acknowledgements: Reported by Juan Escobar from Dreamlab Technologies, Fernando
Munoz from NULL Life CTF Team, and Shungo Kumasaka
Reported to security team 2021-10-06
Update 2.4.51 released 2021-10-07
Affects 2.4.50, 2.4.49
Fixed in Apache HTTP Server 2.4.51
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