CVE-2021-42013: Apache HTTP Server Path Traversal Vulnerability

Reference page built from the source records below, each shown as its source publishes it. Dataset version ref-7ea8b329732f, updated 2026-11-02T23:39:54.475Z.

CISA Known Exploited Vulnerabilities

Name
Apache HTTP Server Path Traversal Vulnerability
Vendor
Apache
Product
HTTP Server
Added to the catalog
2021-11-03
Due date for US federal agencies
2021-11-17
Weaknesses
CWE-22
Catalog version
2026.10.30

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. This CVE ID resolves an incomplete patch for CVE-2021-41773.

Required action (CISA)

Apply updates per vendor instructions.

Ransomware use: CISA marks this vulnerability as known to be used in ransomware campaigns. CISA does not say which group used it.

Links in CISA's notes

Read on 2026-11-02T23:39:54.475Z under licence cisa-kev-cc0@b0067899 from https://www.cisa.gov/sites/default/files/feeds/known_exploited_vulnerabilities.json

NVD analysis

Status
Analyzed
Published
2021-10-07T16:15:09.270
Last modified
2026-06-17T04:09:09.193
Weaknesses
CWE-22, NVD-CWE-Other

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.

MetricScoreSeverityVectorScored by
CVSS 3.19.8CRITICALCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H[email protected] (Primary)
CVSS 3.19.8CRITICALCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H134c704f-9b21-4f2e-91b3-4a467353bcc0 (Secondary)
CVSS 2.07.5HIGHAV:N/AC:L/Au:N/C:P/I:P/A:P[email protected] (Primary)

References

This product uses the NVD API but is not endorsed or certified by the NVD.

Read on 2026-11-02T23:41:59.479Z under licence nvd-api-terms-of-use@ff2a5288 from https://services.nvd.nist.gov/rest/json/cves/2.0?cveId=CVE-2021-42013

CVE record

Title (CNA)
Path Traversal and Remote Code Execution in Apache HTTP Server 2.4.49 and 2.4.50 (incomplete fix of CVE-2021-41773)
Assigner
apache
State
PUBLISHED
Published
2021-10-07T15:50:14.000Z
Updated
2025-10-21T23:25:30.222Z
Problem types
CWE-22 Improper Limitation of a Pathname to a Restricted Directory ('Path Traversal')

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.

References

Read on 2026-11-03T01:09:05.198Z under licence cve-terms-of-use@81bfa2f3 from https://raw.githubusercontent.com/CVEProject/cvelistV5/main/cves/2021/42xxx/CVE-2021-42013.json

Defensive techniques (MITRE D3FEND)

D3FEND maps these defensive techniques to the weakness (CWE) that NVD lists for this CVE, through the digital artifacts the weakness affects. D3FEND does not say they stop this vulnerability.

CWE-22: Improper Limitation of a Pathname to a Restricted Directory ('Path Traversal')

D3FEND ontology version 1.6.0.

Read on 2026-11-02T23:53:56.145Z under licence d3fend-terms-of-use@f98cbc7e from https://d3fend.mitre.org/api/weakness/cwe/CWE-22.json

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Sources and licences

  • CISA

    Source: CISA Catalog of Known Exploited Vulnerabilities, version 2026.10.30, CC0 1.0. Use of this data does not imply endorsement by CISA or DHS.

    CC0 1.0 Universal

  • National Vulnerability Database (NIST)

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    NVD API Terms of Use (NIST publications in the public domain, 17 U.S.C. 105)

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    CVE Program Terms of Use ("CVE Usage" licence)

  • MITRE D3FEND

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    "The MITRE Corporation (MITRE) hereby grants you a non-exclusive, royalty-free license to use D3FEND for research, development, and commercial purposes. Any copy you make for such purposes is authorized provided that you reproduce MITRE's copyright designation and this license in any such copy." Terms: https://d3fend.mitre.org/tou/

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Cite this page

Dragons Eye Ransomware Tracker, "CVE-2021-42013: Apache HTTP Server Path Traversal Vulnerability",
entity page, dataset version ref-7ea8b329732f, updated 2026-11-02T23:39:54.475Z,
https://ransomware-tracker.com/cve/CVE-2021-42013 (accessed 2026-11-03).
Underlying source: CISA Catalog of Known Exploited Vulnerabilities, version 2026.10.30.
Underlying source: National Vulnerability Database (NIST), CVE API 2.0, record last modified 2026-06-17T04:09:09.193.
Underlying source: CVE List (CVE Program, The MITRE Corporation), record updated 2025-10-21T23:25:30.222Z.
Underlying source: MITRE D3FEND, ontology version 1.6.0.

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