CVE-2021-42013

Confirmed PUBLISHED

Path Traversal and Remote Code Execution in Apache HTTP Server 2.4.49 and 2.4.50 (incomplete fix of CVE-2021-41773)

Apache Software Foundation · Apache HTTP Server

Exploited in the wild Used in malware PoC available

Recommended Action

Prioritize remediation. Validate affected assets and apply vendor fixes on an accelerated timeline.

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Confidence

Confirmed

Exploitation Status

Exploited in the wild

Observed in Sensors

Attempts (30d)

—

Unique Attacker IPs

—

CISA KEV

In CISA KEV

CVSS / EPSS

9.8 Critical EPSS 100.0%

At a Glance

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.

ransomware nuclei_scanner metasploit apache malware cisa

CVE Published: Oct 07, 2021
Exploitation Reported: Nov 03, 2021
CVSS: 9.8 Critical
EPSS: 100.0%

Remote Low complexity No user interaction Unauthenticated

Affected Versions

Vendor	Product	Version	Status
Apache Software Foundation	Apache HTTP Server	Apache HTTP Server 2.4.49	Affected
Apache Software Foundation	Apache HTTP Server	Apache HTTP Server 2.4.50	Affected

CVE References

20211007 Apache HTTP Server Vulnerabilties: October 2021 tools.cisco.com · Vendor Advisory https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory...
FEDORA-2021-2a10bc68a4 lists.fedoraproject.org · Vendor Advisory https://lists.fedoraproject.org/archives/list/package-announce%40list...
FEDORA-2021-aaf90ef84a lists.fedoraproject.org · Vendor Advisory https://lists.fedoraproject.org/archives/list/package-announce%40list...
GLSA-202208-20 security.gentoo.org · Vendor Advisory https://security.gentoo.org/glsa/202208-20
JVN#51106450 jvn.jp · Third-Party Advisory http://jvn.jp/en/jp/JVN51106450/index.html

Show 25 more references

[announce] 20211007 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) lists.apache.org · Mailing List https://lists.apache.org/thread.html/r7c795cd45a3384d4d27e57618a215b0...
[httpd-users] 20211007 [users@httpd] 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) lists.apache.org · Mailing List https://lists.apache.org/thread.html/rb5b0e46f179f60b0c70204656bc52fc...
[oss-security] 20211007 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) openwall.com · Mailing List http://www.openwall.com/lists/oss-security/2021/10/07/6
[oss-security] 20211008 Re: 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) openwall.com · Mailing List http://www.openwall.com/lists/oss-security/2021/10/08/1
[httpd-cvs] 20211008 [httpd-site] branch main updated: * Align with CVE-2021-42013 based on the latest findings lists.apache.org · Mailing List https://lists.apache.org/thread.html/r17a4c6ce9aff662efd9459e9d1850ab...
[oss-security] 20211008 Re: 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) openwall.com · Mailing List http://www.openwall.com/lists/oss-security/2021/10/08/2
[oss-security] 20211008 Re: 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) openwall.com · Mailing List http://www.openwall.com/lists/oss-security/2021/10/08/3
[oss-security] 20211008 Re: 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) openwall.com · Mailing List http://www.openwall.com/lists/oss-security/2021/10/08/4
[oss-security] 20211008 Re: 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) openwall.com · Mailing List http://www.openwall.com/lists/oss-security/2021/10/08/6
[oss-security] 20211008 Re: 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) openwall.com · Mailing List http://www.openwall.com/lists/oss-security/2021/10/08/5
[oss-security] 20211009 Re: 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) openwall.com · Mailing List http://www.openwall.com/lists/oss-security/2021/10/09/1
[oss-security] 20211011 Re: 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) openwall.com · Mailing List http://www.openwall.com/lists/oss-security/2021/10/11/4
[oss-security] 20211015 Re: 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) openwall.com · Mailing List http://www.openwall.com/lists/oss-security/2021/10/15/3
[oss-security] 20211016 Re: 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) openwall.com · Mailing List http://www.openwall.com/lists/oss-security/2021/10/16/1
httpd.apache.org/security/vulnerabilities_24.html httpd.apache.org · CVE Record https://httpd.apache.org/security/vulnerabilities_24.html
oracle.com/security-alerts/cpujan2022.html oracle.com · CVE Record https://www.oracle.com/security-alerts/cpujan2022.html
security.netapp.com/advisory/ntap-20211029-0009 security.netapp.com · CVE Record https://security.netapp.com/advisory/ntap-20211029-0009/
packetstormsecurity.com/files/164629/Apache-2.4.49-2.4.50-Traversal-... packetstormsecurity.com · CVE Record http://packetstormsecurity.com/files/164629/Apache-2.4.49-2.4.50-Trav...
packetstormsecurity.com/files/164941/Apache-HTTP-Server-2.4.50-Remot... packetstormsecurity.com · CVE Record http://packetstormsecurity.com/files/164941/Apache-HTTP-Server-2.4.50...
packetstormsecurity.com/files/164501/Apache-HTTP-Server-2.4.50-Path-... packetstormsecurity.com · CVE Record http://packetstormsecurity.com/files/164501/Apache-HTTP-Server-2.4.50...
packetstormsecurity.com/files/164609/Apache-HTTP-Server-2.4.50-Remot... packetstormsecurity.com · CVE Record http://packetstormsecurity.com/files/164609/Apache-HTTP-Server-2.4.50...
packetstormsecurity.com/files/165089/Apache-HTTP-Server-2.4.50-CVE-2... packetstormsecurity.com · CVE Record http://packetstormsecurity.com/files/165089/Apache-HTTP-Server-2.4.50...
oracle.com/security-alerts/cpuapr2022.html oracle.com · CVE Record https://www.oracle.com/security-alerts/cpuapr2022.html
packetstormsecurity.com/files/167397/Apache-2.4.50-Remote-Code-Execu... packetstormsecurity.com · CVE Record http://packetstormsecurity.com/files/167397/Apache-2.4.50-Remote-Code...
povilaika.com/apache-2-4-50-exploit povilaika.com · CVE Record https://www.povilaika.com/apache-2-4-50-exploit/

Recommended Actions

Prioritize remediation. Validate affected assets and apply vendor fixes on an accelerated timeline.
Check enrichment artifacts for scanner coverage and available PoCs before rolling remediation validation.
Use the Pro API to automate enrichment, telemetry, and workflow delivery for VM, SOC, and CTI pipelines.

Known Exploited Vulnerability Sources

Catalogues that list this CVE as a known exploited vulnerability.

Per-source evidence links for KEV attestations are available through the KEVIntel Pro API.

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Source	Added
CISA First	2021-11-03 00:00 UTC
The Shadowserver	2026-06-01 00:00 UTC

Scanner Artifacts

Nuclei and Metasploit references linked to this CVE.

Scanner	Reference	Detected
Nuclei	https://github.com/projectdiscovery/nuclei-templates/blob/main/http/cves/2021/CVE-2021-42013.yaml	Apr 25, 2025
Metasploit	https://github.com/rapid7/metasploit-framework/blob/master/modules/exploits/multi/http/apache_normalize_path_rce.rb	Apr 28, 2025

CVSS Scores

CVSS v3.1 9.8 Critical

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

CVSS v2.0 7.5 High

AV:N/AC:L/Au:N/C:P/I:P/A:P

Exploitation Status

Exploited in the wild

Recorded 2021-11-03 00:00:00 UTC · CISA

Used in malware

Recorded 2021-11-03 00:00:00 UTC · CISA

Proof of concept available

Recorded 2021-10-07 18:31:29 UTC · GitHub

Weaknesses (CWE)

CWE-22

Improper Limitation of a Pathname to a Restricted Directory ('Path Traversal')

Scanner Integrations

Scanner	Reference	Detected
Metasploit	https://github.com/rapid7/metasploit-framework/blob/master/modules/exploits/multi/http/apache_normalize_path_rce.rb	Apr 28, 2025
Nuclei	https://github.com/projectdiscovery/nuclei-templates/blob/main/http/cves/2021/CVE-2021-42013.yaml	Apr 25, 2025

Potential Proof of Concepts

These PoCs are unverified and could contain malware. Use at your own risk.

BassoNicolas/CVE-2021-42013

github · Created 2024-04-07 16:04:06 UTC · 3 stars

CVE-2021-42013 Vulnerability Scanner This Python script checks for the Remote Code Execution (RCE) vulnerability (CVE-2021-42013) in Apache 2.4.50.

K3ysTr0K3R/CVE-2021-42013-EXPLOIT

github · Created 2023-08-25 19:51:01 UTC · 2 stars

A PoC exploit for CVE-2021-42013 - Apache 2.4.49 & 2.4.50 Remote Code Execution

12345qwert123456/CVE-2021-42013

github · Created 2022-11-18 17:53:46 UTC · 0 stars

Vulnerable configuration Apache HTTP Server version 2.4.49/2.4.50

asaotomo/CVE-2021-42013-Apache-RCE-Poc-Exp

github · Created 2021-12-23 14:46:41 UTC · 10 stars

Apache 远程代码执行（CVE-2021-42013）批量检测工具：Apache HTTP Server是美国阿帕奇（Apache）基金会的一款开源网页服务器。该服务器具有快速、可靠且可通过简单的API进行扩充的特点，发现 Apache HTTP Server 2.4.50 中针对 CVE-2021-41773 的修复不够充分。攻击者可以使用路径遍历攻击将 URL 映射到由类似别名的指令配置的目录之外的文件。如果这些目录之外的文件不受通常的默认配置“要求全部拒绝”的保护，则这些请求可能会成功。如果还为这些别名路径启用了 CGI 脚本，则这可能允许远程代码执行。此问题仅影响 Apache 2.4.49 和 Apache 2.4.50，而不影响更早版本。

TheLastVvV/CVE-2021-42013_Reverse-Shell

github · Created 2021-10-24 12:57:55 UTC · 7 stars

PoC CVE-2021-42013 reverse shell Apache 2.4.50 with CGI

TheLastVvV/CVE-2021-42013

github · Created 2021-10-23 21:58:44 UTC · 2 stars

Poc CVE-2021-42013 - Apache 2.4.50 without CGI

andrea-mattioli/apache-exploit-CVE-2021-42013

github · Created 2021-10-07 18:31:29 UTC · 9 stars

Exploit with integrated shodan search

Apache 2.4.49/2.4.50 - Path Traversal and Remote Code Execution

nuclei · Created Unknown

apache_normalize_path_rce

metasploit · Created Unknown

Metasploit module for CVE-2021-42013

Timeline

Key exploitation, disclosure, scanner coverage, and KEV attestation events for this CVE.

1 Jun 2026 00:00 UTC about 2 months ago

1 Jun 2026 00:00 UTC · about 2 months ago

KEV confirmed by The Shadowserver

Exploitation attested by an external source
28 Apr 2025 15:02 UTC about 1 year ago

28 Apr 2025 15:02 UTC · about 1 year ago

Metasploit module available

Exploit module available
25 Apr 2025 00:00 UTC about 1 year ago

25 Apr 2025 00:00 UTC · about 1 year ago

Nuclei template available

Scanner coverage available
3 Nov 2021 00:00 UTC over 4 years ago

3 Nov 2021 00:00 UTC · over 4 years ago

Added to CISA KEV

Listed in the CISA Known Exploited Vulnerabilities catalog
3 Nov 2021 00:00 UTC over 4 years ago

3 Nov 2021 00:00 UTC · over 4 years ago

First public exploitation report

Exploit observed in malware
7 Oct 2021 18:31 UTC almost 5 years ago

7 Oct 2021 18:31 UTC · almost 5 years ago

Public PoC available

Public proof-of-concept code published
7 Oct 2021 15:50 UTC almost 5 years ago

7 Oct 2021 15:50 UTC · almost 5 years ago

CVE published

Vulnerability disclosed publicly
6 Oct 2021 00:00 UTC almost 5 years ago

6 Oct 2021 00:00 UTC · almost 5 years ago

CVE ID reserved

Identifier reserved by the CNA

Automate This Intelligence with the Pro API

Confidence scoring, exploit status, sensor telemetry, PoCs, scanner integrations, mentions, and tags are available programmatically for VM, SOC, and CTI workflows.

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Pro API Example

GET /api/v2/pro/kevs/CVE-2021-42013

{
  "cve_id": "CVE-2021-42013",
  "title": "Path Traversal and Remote Code Execution in Apache HTTP Server 2.4.49 and 2.4...",
  "affected_vendor": "Apache Software Foundation",
  "affected_product": "Apache HTTP Server",
  "affected_versions": [
    { "vendor": "...", "product": "...", "status": "affected", "display_label": "..." }
  ],
  "confidence": "Confirmed",
  "cvss_score": 9.8,
  "epss_score": 0.99964,
  "exploit_status": {
    "exploited_in_the_wild": true,
    "active_exploitation_observed": false
  },
  "sensor_telemetry": { "...": "Pro API fields" },
  "proof_of_concepts": [ "..." ],
  "scanner_integrations": [ "..." ]
}

The free JSON API returns basic KEV fields only. Confidence, telemetry, and artifact enrichment require Pro API access.

CVE-2021-42013

At a Glance

Affected Versions

CVE References

Recommended Actions

Known Exploited Vulnerability Sources

Scanner Artifacts

Virtual Patch

CVSS Scores

Exploitation Status

Weaknesses (CWE)

Scanner Integrations

Potential Proof of Concepts

Timeline

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