CVE-2021-4189 (GCVE-0-2021-4189)
Vulnerability from cvelistv5 – Published: 2022-08-24 00:00 – Updated: 2025-12-17 21:36
VLAI
EPSS
VEX
Summary
A flaw was found in Python, specifically in the FTP (File Transfer Protocol) client library in PASV (passive) mode. The issue is how the FTP client trusts the host from the PASV response by default. This flaw allows an attacker to set up a malicious FTP server that can trick FTP clients into connecting back to a given IP address and port. This vulnerability could lead to FTP client scanning ports, which otherwise would not have been possible.
Severity
5.3 (Medium)
SSVC
Exploitation: none
Automatable: yes
Technical Impact: partial
CISA Coordinator (v2.0.3)
CWE
- Not-Known
- CWE-252 - Unchecked Return Value
Assigner
References
10 references
Impacted products
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"redhat_vex": {
"aggregate_severity": "Moderate",
"current_release_date": "2026-06-28T07:49:05+00:00",
"cve": "CVE-2021-4189",
"id": "CVE-2021-4189",
"initial_release_date": "2021-12-21T00:00:00+00:00",
"product_status:fixed": "480",
"product_status:known_affected": "23",
"product_status:known_not_affected": "168",
"source": "Red Hat CSAF VEX",
"status": "final",
"title": "python: ftplib should not use the host from the PASV response",
"url": "https://security.access.redhat.com/data/csaf/v2/vex/2021/cve-2021-4189.json",
"version": "3"
},
"vulnrichment": {
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"cveMetadata": "{\"cveId\": \"CVE-2021-4189\", \"state\": \"PUBLISHED\", \"dateUpdated\": \"2025-12-17T21:36:07.876Z\", \"dateReserved\": \"2021-12-29T00:00:00.000Z\", \"assignerOrgId\": \"53f830b8-0a3f-465b-8143-3b8a9948e749\", \"datePublished\": \"2022-08-24T00:00:00.000Z\", \"assignerShortName\": \"redhat\"}",
"dataType": "CVE_RECORD",
"dataVersion": "5.2"
}
}
}
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Experimental. This forecast is provided for visualization only and may change without notice. Do not use it for operational decisions.
Forecast uses a logistic model when the trend is rising, or an exponential decay model when the trend is falling. Fitted via linearized least squares.
Sightings
| Author | Source | Type | Date | Other |
|---|
Nomenclature
- Seen: The vulnerability was mentioned, discussed, or observed by the user.
- Confirmed: The vulnerability has been validated from an analyst's perspective.
- Published Proof of Concept: A public proof of concept is available for this vulnerability.
- Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
- Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
- Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
- Not confirmed: The user expressed doubt about the validity of the vulnerability.
- Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.
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