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CVE-2021-41773

Apache HTTP Server Path Traversal Vulnerability

Published Oct 5, 2021 · updated Jun 16, 2026 · apache http server

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.

Timeline

Detection, updates, and resolution for this record.

  1. Oct 5, 2021 · Catalog

    Detected

    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 ali

  2. Nov 3, 2021 · CISA KEV

    Known exploited

    Apply updates per vendor instructions.

  3. Nov 17, 2021 · CISA KEV

    Remediation due

    Apply updates per vendor instructions.

  4. Jun 16, 2026 · Catalog

    Updated

    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 ali

Required action

Apply updates per vendor instructions.

CISA due date Nov 17, 2021

Affected

  • cpe apache/http server2.4.49
  • cpe fedoraproject/fedora34
  • cpe fedoraproject/fedora35
  • cpe netapp/cloud backupversion unspecified
  • cpe oracle/instantis enterprisetrack17.1
  • cpe oracle/instantis enterprisetrack17.2
  • cpe oracle/instantis enterprisetrack17.3
  • vendor Apache HTTP Serverversion unspecified

Sources

  • CISA KEVCVE-2021-41773

    Apache HTTP Server contains a path traversal vulnerability that allows an attacker to perform remote code execution if files outside directories configured by Alias-like directives are not under default �require all denied� or if CGI scripts are enabled. The original patch issued under this CVE ID is insufficient, please review remediation information under CVE-2021-42013.

    cisa.gov
  • CVE.orgCVE-2021-41773

    Official CVE identifier

    cve.org
  • FIRST EPSSCVE-2021-41773

    30-day exploitation probability 100.0%

    first.org
  • Exploit Database50383

    Public archive entry. The exploit body is not stored here.

    exploit-db.com
  • Exploit Database50512

    Public archive entry. The exploit body is not stored here.

    exploit-db.com
  • Metasploit Modulesauxiliary_scanner/http/apache_normalize_path

    Public module reference (normal). Module source is not copied into this catalog.

    rapid7.com
  • Metasploit Modulesexploit_multi/http/apache_normalize_path_rce

    Public module reference (excellent). Module source is not copied into this catalog.

    rapid7.com
  • NIST NVDCVE-2021-41773

    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 usu

    nvd.nist.gov

References