CISA KEV entry
CVE-2021-41773Apache HTTP Server Path Traversal Vulnerability
Apache HTTP Server. Added to the CISA Known Exploited Vulnerabilities catalogue on 3 November 2021.
Data status: a source is stale
Last synced CISA catalogue version 2026.11.04 (released 4 November 2026) 1,768 entries Updated manually
- Date added
- 2021-11-03
- Federal due date
- 2021-11-17 14 days after it was added; passed at the sync of 2026-11-05
- Known ransomware use
- Known
- Forensic triage (BOD 26-04)
- No
- CVSS
- 9.8 Critical CVSS 3.1, scored by nvd@nist.gov
- EPSS
- 99.99% percentile 99.9, scored 2026-11-04
- CISA SSVC
- Exploitation active, automatable yes, technical impact total
- NVD status
- Analyzed published 2021-10-05, 29 days before the KEV listing
BOD 26-04 remediation window
With CISA's SSVC answers for this CVE (automatable: yes, technical impact: total), BOD 26-04 Table 1 gives 3 days and forensic triage on a publicly exposed asset (row 1) and 3 days and forensic triage on an asset that is not publicly exposed (row 9) S06. The catalogue due date, 14 days after the date added, was set before BOD 26-04 took effect on 10 June 2026 S06. The directive binds US federal civilian executive branch agencies only.
What CISA says
Short description
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.
Required action
Apply updates per vendor instructions.
Notes
https://nvd.nist.gov/vuln/detail/CVE-2021-41773
CWE in the catalogue
CWE-22
Official links
- CISA KEV catalogue entry cisa.gov
- NVD record nvd.nist.gov
Vendor advisory and patch links
References NVD tags Vendor Advisory or Patch, exactly as NVD lists them.
- http://www.openwall.com/lists/oss-security/2021/10/11/4 Mailing List, Patch, Third Party Advisory
- http://www.openwall.com/lists/oss-security/2021/10/15/3 Mailing List, Patch, Third Party Advisory
- https://httpd.apache.org/security/vulnerabilities_24.html Release Notes, Vendor Advisory
- https://lists.apache.org/thread.html/r17a4c6ce9aff662efd9459e9d1850ab4a611cb23392fc68264c72cb3%40%3Ccvs.httpd.apache.org%3E Mailing List, Patch
- https://www.oracle.com/security-alerts/cpujan2022.html Patch, Third Party Advisory
Links in CISA's notes
NVD details
- CWE (NVD)
- CWE-22 by security@apache.org
- CVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H- CVSS versions in NVD
- V2, V31
- Last modified in NVD
- 2026-06-17T04:08:53.933
Where each value comes from
| Field | Source | Fetched, UTC | State |
|---|---|---|---|
| Catalogue fields | CISA KEV JSON, version 2026.11.04 | 2026-11-05 11:38 | current |
| NVD published, status, CVSS, CWE, vendor links | NVD CVE API 2.0; CVSS: NVD (nvd@nist.gov) | 2026-11-03 12:37 | current at 2026-11-05 11:38 |
| EPSS | FIRST EPSS API, scores of 2026-11-04 | 2026-11-05 11:38 | current |
| CISA SSVC | CISA ADP (via NVD), record of 2025-02-04 | 2026-11-03 12:37 | current |
This product uses data from the NVD API but is not endorsed or certified by the NVD. CISA does not endorse Sysprobs. Methodology.