CVE-2021-42013

9.8 CRITICAL CISA KEV - Actively Exploited
Published: October 07, 2021 Modified: October 27, 2025
View on NVD

Description

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.

AI Explanation

Get an AI-powered plain-language explanation of this vulnerability and remediation steps.

Login to generate AI explanation

CVSS v3.x Details

0.0 Low Medium High Critical 10.0
Vector String
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

References to Advisories, Solutions, and Tools

Patch Vendor Advisory Exploit Third Party Advisory
http://jvn.jp/en/jp/JVN51106450/index.html
Source: security@apache.org
Third Party Advisory
http://packetstormsecurity.com/files/164501/Apache-HTTP-Server-2.4.50-Path-Traversal-Code-Execution.html
Source: security@apache.org
Exploit Third Party Advisory VDB Entry
http://packetstormsecurity.com/files/164609/Apache-HTTP-Server-2.4.50-Remote-Code-Execution.html
Source: security@apache.org
Exploit Third Party Advisory VDB Entry
http://packetstormsecurity.com/files/164629/Apache-2.4.49-2.4.50-Traversal-Remote-Code-Execution.html
Source: security@apache.org
Exploit Third Party Advisory VDB Entry
http://packetstormsecurity.com/files/164941/Apache-HTTP-Server-2.4.50-Remote-Code-Execution.html
Source: security@apache.org
Exploit Third Party Advisory VDB Entry
http://packetstormsecurity.com/files/165089/Apache-HTTP-Server-2.4.50-CVE-2021-42013-Exploitation.html
Source: security@apache.org
Third Party Advisory VDB Entry
http://packetstormsecurity.com/files/167397/Apache-2.4.50-Remote-Code-Execution.html
Source: security@apache.org
Exploit Third Party Advisory VDB Entry
http://www.openwall.com/lists/oss-security/2021/10/07/6
Source: security@apache.org
Mailing List Third Party Advisory
http://www.openwall.com/lists/oss-security/2021/10/08/1
Source: security@apache.org
Mailing List Third Party Advisory
http://www.openwall.com/lists/oss-security/2021/10/08/2
Source: security@apache.org
Mailing List Third Party Advisory
http://www.openwall.com/lists/oss-security/2021/10/08/3
Source: security@apache.org
Mailing List Third Party Advisory
http://www.openwall.com/lists/oss-security/2021/10/08/4
Source: security@apache.org
Mailing List Third Party Advisory
http://www.openwall.com/lists/oss-security/2021/10/08/5
Source: security@apache.org
Mailing List Third Party Advisory
http://www.openwall.com/lists/oss-security/2021/10/08/6
Source: security@apache.org
Mailing List Third Party Advisory
http://www.openwall.com/lists/oss-security/2021/10/09/1
Source: security@apache.org
Mailing List Third Party Advisory
http://www.openwall.com/lists/oss-security/2021/10/11/4
Source: security@apache.org
Mailing List Third Party Advisory
http://www.openwall.com/lists/oss-security/2021/10/15/3
Source: security@apache.org
Mailing List Third Party Advisory
http://www.openwall.com/lists/oss-security/2021/10/16/1
Source: security@apache.org
Mailing List Third Party Advisory
https://httpd.apache.org/security/vulnerabilities_24.html
Source: security@apache.org
Release Notes Vendor Advisory
https://lists.apache.org/thread.html/r17a4c6ce9aff662efd9459e9d1850ab4a611cb23392fc68264c72cb3%40%3Ccvs.httpd.apache.org%3E
Source: security@apache.org
Mailing List Patch
https://lists.apache.org/thread.html/r7c795cd45a3384d4d27e57618a215b0ed19cb6ca8eb070061ad5d837%40%3Cannounce.apache.org%3E
Source: security@apache.org
Mailing List
https://lists.apache.org/thread.html/rb5b0e46f179f60b0c70204656bc52fcb558e961cb4d06a971e9e3efb%40%3Cusers.httpd.apache.org%3E
Source: security@apache.org
Mailing List
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/RMIIEFINL6FUIOPD2A3M5XC6DH45Y3CC/
Source: security@apache.org
Release Notes
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/WS5RVHOIIRECG65ZBTZY7IEJVWQSQPG3/
Source: security@apache.org
Release Notes
https://security.gentoo.org/glsa/202208-20
Source: security@apache.org
Third Party Advisory
https://security.netapp.com/advisory/ntap-20211029-0009/
Source: security@apache.org
Third Party Advisory
https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-apache-httpd-pathtrv-LAzg68cZ
Source: security@apache.org
Third Party Advisory
https://www.oracle.com/security-alerts/cpuapr2022.html
Source: security@apache.org
Patch Third Party Advisory
https://www.oracle.com/security-alerts/cpujan2022.html
Source: security@apache.org
Patch Third Party Advisory
https://www.povilaika.com/apache-2-4-50-exploit/
Source: security@apache.org
Exploit Third Party Advisory
http://jvn.jp/en/jp/JVN51106450/index.html
Source: af854a3a-2127-422b-91ae-364da2661108
Third Party Advisory
http://packetstormsecurity.com/files/164501/Apache-HTTP-Server-2.4.50-Path-Traversal-Code-Execution.html
Source: af854a3a-2127-422b-91ae-364da2661108
Exploit Third Party Advisory VDB Entry
http://packetstormsecurity.com/files/164609/Apache-HTTP-Server-2.4.50-Remote-Code-Execution.html
Source: af854a3a-2127-422b-91ae-364da2661108
Exploit Third Party Advisory VDB Entry
http://packetstormsecurity.com/files/164629/Apache-2.4.49-2.4.50-Traversal-Remote-Code-Execution.html
Source: af854a3a-2127-422b-91ae-364da2661108
Exploit Third Party Advisory VDB Entry
http://packetstormsecurity.com/files/164941/Apache-HTTP-Server-2.4.50-Remote-Code-Execution.html
Source: af854a3a-2127-422b-91ae-364da2661108
Exploit Third Party Advisory VDB Entry
http://packetstormsecurity.com/files/165089/Apache-HTTP-Server-2.4.50-CVE-2021-42013-Exploitation.html
Source: af854a3a-2127-422b-91ae-364da2661108
Third Party Advisory VDB Entry
http://packetstormsecurity.com/files/167397/Apache-2.4.50-Remote-Code-Execution.html
Source: af854a3a-2127-422b-91ae-364da2661108
Exploit Third Party Advisory VDB Entry
http://www.openwall.com/lists/oss-security/2021/10/07/6
Source: af854a3a-2127-422b-91ae-364da2661108
Mailing List Third Party Advisory
http://www.openwall.com/lists/oss-security/2021/10/08/1
Source: af854a3a-2127-422b-91ae-364da2661108
Mailing List Third Party Advisory
http://www.openwall.com/lists/oss-security/2021/10/08/2
Source: af854a3a-2127-422b-91ae-364da2661108
Mailing List Third Party Advisory
http://www.openwall.com/lists/oss-security/2021/10/08/3
Source: af854a3a-2127-422b-91ae-364da2661108
Mailing List Third Party Advisory
http://www.openwall.com/lists/oss-security/2021/10/08/4
Source: af854a3a-2127-422b-91ae-364da2661108
Mailing List Third Party Advisory
http://www.openwall.com/lists/oss-security/2021/10/08/5
Source: af854a3a-2127-422b-91ae-364da2661108
Mailing List Third Party Advisory
http://www.openwall.com/lists/oss-security/2021/10/08/6
Source: af854a3a-2127-422b-91ae-364da2661108
Mailing List Third Party Advisory
http://www.openwall.com/lists/oss-security/2021/10/09/1
Source: af854a3a-2127-422b-91ae-364da2661108
Mailing List Third Party Advisory
http://www.openwall.com/lists/oss-security/2021/10/11/4
Source: af854a3a-2127-422b-91ae-364da2661108
Mailing List Third Party Advisory
http://www.openwall.com/lists/oss-security/2021/10/15/3
Source: af854a3a-2127-422b-91ae-364da2661108
Mailing List Third Party Advisory
http://www.openwall.com/lists/oss-security/2021/10/16/1
Source: af854a3a-2127-422b-91ae-364da2661108
Mailing List Third Party Advisory
https://httpd.apache.org/security/vulnerabilities_24.html
Source: af854a3a-2127-422b-91ae-364da2661108
Release Notes Vendor Advisory
https://lists.apache.org/thread.html/r17a4c6ce9aff662efd9459e9d1850ab4a611cb23392fc68264c72cb3%40%3Ccvs.httpd.apache.org%3E
Source: af854a3a-2127-422b-91ae-364da2661108
Mailing List Patch
https://lists.apache.org/thread.html/r7c795cd45a3384d4d27e57618a215b0ed19cb6ca8eb070061ad5d837%40%3Cannounce.apache.org%3E
Source: af854a3a-2127-422b-91ae-364da2661108
Mailing List
https://lists.apache.org/thread.html/rb5b0e46f179f60b0c70204656bc52fcb558e961cb4d06a971e9e3efb%40%3Cusers.httpd.apache.org%3E
Source: af854a3a-2127-422b-91ae-364da2661108
Mailing List
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/RMIIEFINL6FUIOPD2A3M5XC6DH45Y3CC/
Source: af854a3a-2127-422b-91ae-364da2661108
Release Notes
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/WS5RVHOIIRECG65ZBTZY7IEJVWQSQPG3/
Source: af854a3a-2127-422b-91ae-364da2661108
Release Notes
https://security.gentoo.org/glsa/202208-20
Source: af854a3a-2127-422b-91ae-364da2661108
Third Party Advisory
https://security.netapp.com/advisory/ntap-20211029-0009/
Source: af854a3a-2127-422b-91ae-364da2661108
Third Party Advisory
https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-apache-httpd-pathtrv-LAzg68cZ
Source: af854a3a-2127-422b-91ae-364da2661108
Third Party Advisory
https://www.oracle.com/security-alerts/cpuapr2022.html
Source: af854a3a-2127-422b-91ae-364da2661108
Patch Third Party Advisory
https://www.oracle.com/security-alerts/cpujan2022.html
Source: af854a3a-2127-422b-91ae-364da2661108
Patch Third Party Advisory
https://www.povilaika.com/apache-2-4-50-exploit/
Source: af854a3a-2127-422b-91ae-364da2661108
Exploit Third Party Advisory
https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2021-42013
Source: 134c704f-9b21-4f2e-91b3-4a467353bcc0
US Government Resource

61 reference(s) from NVD

Quick Stats

CVSS v3 Score
9.8 / 10.0
EPSS (Exploit Probability)
94.4%
100th percentile
Exploitation Status
Actively Exploited
Remediation due: 2021-11-17

Weaknesses (CWE)

CWE-22 CWE-22

Affected Vendors

apache fedoraproject oracle netapp

Related CVEs

CVE-2025-52691 10.0
CVE-2025-15168 7.3
CVE-2025-15167 7.3
CVE-2025-15166 7.3
CVE-2025-15165 7.3