USN-6037-1 (UBUNTU-CVE-2021-37533)
Vulnerability from osv_ubuntu – Published: 2023-04-28 10:19 – Updated: 2026-06-25 10:46 – Source website
VLAI
Summary
Apache Commons Net vulnerability
Details
ZeddYu Lu discovered that the FTP client from Apache Commons Net trusted the host from PASV responses by default. A remote attacker with a malicious FTP server could redirect the client to another server, which could possibly result in leaked information about services running on the private network of the client.
References
| URL | Type | |
|---|---|---|
{
"affected": [
{
"database_specific": {
"cves_map": {
"cves": [
{
"id": "CVE-2021-37533",
"severity": [
{
"score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:N/A:N",
"type": "CVSS_V3"
},
{
"score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:N/A:N",
"type": "CVSS_V3"
},
{
"score": "medium",
"type": "Ubuntu"
}
]
}
],
"ecosystem": "Ubuntu:Pro:16.04:LTS"
}
},
"ecosystem_specific": {
"availability": "Available with Ubuntu Pro: https://ubuntu.com/pro",
"binaries": [
{
"binary_name": "libcommons-net-java",
"binary_version": "3.4-2ubuntu2+esm1"
}
]
},
"package": {
"ecosystem": "Ubuntu:Pro:16.04:LTS",
"name": "libcommons-net-java",
"purl": "pkg:deb/ubuntu/libcommons-net-java@3.4-2ubuntu2+esm1?arch=source\u0026distro=esm-apps/xenial"
},
"ranges": [
{
"events": [
{
"introduced": "0"
},
{
"fixed": "3.4-2ubuntu2+esm1"
}
],
"type": "ECOSYSTEM"
}
],
"versions": [
"3.3-2",
"3.4-1",
"3.4-2",
"3.4-2ubuntu2"
]
},
{
"database_specific": {
"cves_map": {
"cves": [
{
"id": "CVE-2021-37533",
"severity": [
{
"score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:N/A:N",
"type": "CVSS_V3"
},
{
"score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:N/A:N",
"type": "CVSS_V3"
},
{
"score": "medium",
"type": "Ubuntu"
}
]
}
],
"ecosystem": "Ubuntu:18.04:LTS"
}
},
"ecosystem_specific": {
"availability": "No subscription required",
"binaries": [
{
"binary_name": "libcommons-net-java",
"binary_version": "3.6-1+deb11u1build0.18.04.1"
}
]
},
"package": {
"ecosystem": "Ubuntu:18.04:LTS",
"name": "libcommons-net-java",
"purl": "pkg:deb/ubuntu/libcommons-net-java@3.6-1+deb11u1build0.18.04.1?arch=source\u0026distro=bionic"
},
"ranges": [
{
"events": [
{
"introduced": "0"
},
{
"fixed": "3.6-1+deb11u1build0.18.04.1"
}
],
"type": "ECOSYSTEM"
}
],
"versions": [
"3.6-1"
]
},
{
"database_specific": {
"cves_map": {
"cves": [
{
"id": "CVE-2021-37533",
"severity": [
{
"score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:N/A:N",
"type": "CVSS_V3"
},
{
"score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:N/A:N",
"type": "CVSS_V3"
},
{
"score": "medium",
"type": "Ubuntu"
}
]
}
],
"ecosystem": "Ubuntu:20.04:LTS"
}
},
"ecosystem_specific": {
"availability": "No subscription required",
"binaries": [
{
"binary_name": "libcommons-net-java",
"binary_version": "3.6-1+deb11u1build0.20.04.1"
}
]
},
"package": {
"ecosystem": "Ubuntu:20.04:LTS",
"name": "libcommons-net-java",
"purl": "pkg:deb/ubuntu/libcommons-net-java@3.6-1+deb11u1build0.20.04.1?arch=source\u0026distro=focal"
},
"ranges": [
{
"events": [
{
"introduced": "0"
},
{
"fixed": "3.6-1+deb11u1build0.20.04.1"
}
],
"type": "ECOSYSTEM"
}
],
"versions": [
"3.6-1"
]
},
{
"database_specific": {
"cves_map": {
"cves": [
{
"id": "CVE-2021-37533",
"severity": [
{
"score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:N/A:N",
"type": "CVSS_V3"
},
{
"score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:N/A:N",
"type": "CVSS_V3"
},
{
"score": "medium",
"type": "Ubuntu"
}
]
}
],
"ecosystem": "Ubuntu:22.04:LTS"
}
},
"ecosystem_specific": {
"availability": "No subscription required",
"binaries": [
{
"binary_name": "libcommons-net-java",
"binary_version": "3.6-1+deb11u1build0.22.04.1"
}
]
},
"package": {
"ecosystem": "Ubuntu:22.04:LTS",
"name": "libcommons-net-java",
"purl": "pkg:deb/ubuntu/libcommons-net-java@3.6-1+deb11u1build0.22.04.1?arch=source\u0026distro=jammy"
},
"ranges": [
{
"events": [
{
"introduced": "0"
},
{
"fixed": "3.6-1+deb11u1build0.22.04.1"
}
],
"type": "ECOSYSTEM"
}
],
"versions": [
"3.6-1"
]
}
],
"aliases": [],
"details": "ZeddYu Lu discovered that the FTP client from Apache Commons Net trusted\nthe host from PASV responses by default. A remote attacker with a\nmalicious FTP server could redirect the client to another server, which\ncould possibly result in leaked information about services running on the\nprivate network of the client.\n",
"id": "USN-6037-1",
"modified": "2026-06-25T10:46:12Z",
"published": "2023-04-28T10:19:40Z",
"references": [
{
"type": "ADVISORY",
"url": "https://ubuntu.com/security/notices/USN-6037-1"
},
{
"type": "REPORT",
"url": "https://ubuntu.com/security/CVE-2021-37533"
}
],
"related": [],
"schema_version": "1.7.0",
"summary": "Apache Commons Net vulnerability",
"upstream": [
"UBUNTU-CVE-2021-37533"
]
}
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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.
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- 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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The MITRE ATT&CK techniques below are AI-generated suggestions, inferred from the description of the
vulnerability by the CIRCL/vulnerability-attack-technique-classification-roberta-base
model, served locally by ML-Gateway.
They have not been verified by an analyst and are provided for guidance only.
The approach is described in our paper Mapping CVEs to MITRE ATT&CK Techniques: A Curated Gold-Set Classifier and the Limits of LLM-Assisted Label Expansion.
Browse all ATT&CK techniques and the vulnerabilities related to each.
The approach is described in our paper Mapping CVEs to MITRE ATT&CK Techniques: A Curated Gold-Set Classifier and the Limits of LLM-Assisted Label Expansion.
Browse all ATT&CK techniques and the vulnerabilities related to each.
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Related by attack behaviour
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