UnratedFix available
python3.7, python3.8 vulnerabilities
Type: advisorySources: OSV
It was discovered that the urllib.request.AbstractBasicAuthHandler class in Python contains regex allowing for catastrophic backtracking. Specially crafted traffic from a malicious HTTP server could cause a regular expression denial of service (ReDoS) condition for a client. (CVE-2020-8492) It was discovered that the urllib.request.AbstractBasicAuthHandler class in Python contains regex with a quadratic worst-case time complexity. Specially crafted traffic from a malicious HTTP server could cause a regular expression denial of service (ReDoS) condition for a client. (CVE-2021-3733) It was discovered that the Python urllib http client could enter into an infinite loop when incorrectly handling certain server responses (100 Continue response). Specially crafted traffic from a malicious HTTP server could cause a denial of service (DoS) condition for a client. (CVE-2021-3737)
- Products
- python3.7, python3.8
- Affected versions
- 3.7.0-1~18.04, 3.7.0~a2-1, 3.7.0~a3-1, 3.7.0~a3-2, 3.7.0~a3-3, 3.7.0~a4-1, 3.7.0~b1-1, 3.7.0~b1-1build1, 3.7.0~b2-1, 3.7.0~b3-1, 3.7.1-1~18.04, 3.7.3-2~18.04.1, 3.7.5-2~18.04, 3.7.5-2~18.04.4, 3.8.0-3~18.04, 3.8.0-3~18.04.1
- Fixed versions
- 3.7.5-2ubuntu1~18.04.2, 3.8.0-3ubuntu1~18.04.2
- CVEs
- CVE-2020-8492, CVE-2021-3733, CVE-2021-3737
- Confirmed fixed CVEs
- Not specified
- Updated in this feed
- 28 Oct 2026, 10:04 UTC · Revision 1
Source evidence
It was discovered that the urllib.request.AbstractBasicAuthHandler class in Python contains regex allowing for catastrophic backtracking. Specially crafted traffic from a malicious HTTP server could cause a regular expression denial of service (ReDoS) condition for a client. (CVE-2020-8492) It was discovered that the urllib.request.AbstractBasicAuthHandler class in Python contains regex with a quadratic worst-case time complexity. Specially crafted traffic from a malicious HTTP server could cause a regular expression denial of service (ReDoS) condition for a client. (CVE-2021-3733) It was discovered that the Python urllib http client could enter into an infinite loop when incorrectly handling certain server responses (100 Continue response). Specially crafted traffic from a malicious HTTP server could cause a denial of service (DoS) condition for a client. (CVE-2021-3737)
osv:USN-5200-1
python3.7
Fixed versions: 3.7.5-2ubuntu1~18.04.2
python3.8
Fixed versions: 3.8.0-3ubuntu1~18.04.2
Complete source record
{
"id": "9a4fb08ca9a5ec8d70649381b1457720cef5893abdc29222dfe1af8fe44bb59b",
"url": "https://osv.dev/vulnerability/USN-5200-1",
"method": "structured",
"payload": {
"kind": "advisory",
"title": "python3.7, python3.8 vulnerabilities",
"summary": "It was discovered that the urllib.request.AbstractBasicAuthHandler class in Python contains regex allowing for catastrophic backtracking. Specially crafted traffic from a malicious HTTP server could cause a regular expression denial of service (ReDoS) condition for a client. (CVE-2020-8492) It was discovered that the urllib.request.AbstractBasicAuthHandler class in Python contains regex with a quadratic worst-case time complexity. Specially crafted traffic from a malicious HTTP server could cause a regular expression denial of service (ReDoS) condition for a client. (CVE-2021-3733) It was discovered that the Python urllib http client could enter into an infinite loop when incorrectly handling certain server responses (100 Continue response). Specially crafted traffic from a malicious HTTP server could cause a denial of service (DoS) condition for a client. (CVE-2021-3737)",
"evidence": "osv:USN-5200-1",
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"evidence": "/affected/0/ranges"
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"evidence": "/affected/0/versions"
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"evidence": "/affected/0/versions"
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{
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"evidence": "/affected/0/versions"
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{
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{
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{
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"evidence": "/affected/0/versions"
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{
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"evidence": "/affected/0/versions"
},
{
"value": "3.7.0-1~18.04",
"evidence": "/affected/0/versions"
},
{
"value": "3.7.1-1~18.04",
"evidence": "/affected/0/versions"
},
{
"value": "3.7.3-2~18.04.1",
"evidence": "/affected/0/versions"
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{
"value": "3.7.5-2~18.04",
"evidence": "/affected/0/versions"
},
{
"value": "3.7.5-2~18.04.4",
"evidence": "/affected/0/versions"
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},
{
"name": {
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"evidence": "/affected/1/package/name"
},
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{
"value": "3.8.0-3ubuntu1~18.04.2",
"evidence": "/affected/1/ranges"
}
],
"affected_versions": [
{
"value": "3.8.0-3~18.04",
"evidence": "/affected/1/versions"
},
{
"value": "3.8.0-3~18.04.1",
"evidence": "/affected/1/versions"
}
]
}
],
"severity": "unknown",
"structured": {
"id": "USN-5200-1",
"aliases": [
"USN-5200-1"
],
"affected": [
{
"ranges": [
{
"type": "ECOSYSTEM",
"events": [
{
"introduced": "0"
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{
"fixed": "3.7.5-2ubuntu1~18.04.2"
}
]
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],
"package": {
"name": "python3.7",
"purl": "pkg:deb/ubuntu/python3.7?arch=source&distro=bionic",
"ecosystem": "Ubuntu:18.04:LTS"
},
"versions": [
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"3.7.0~a3-1",
"3.7.0~a3-2",
"3.7.0~a3-3",
"3.7.0~a4-1",
"3.7.0~b1-1",
"3.7.0~b1-1build1",
"3.7.0~b2-1",
"3.7.0~b3-1",
"3.7.0-1~18.04",
"3.7.1-1~18.04",
"3.7.3-2~18.04.1",
"3.7.5-2~18.04",
"3.7.5-2~18.04.4"
],
"database_specific": {
"source": "https://github.com/canonical/ubuntu-security-notices/blob/main/osv/usn/USN-5200-1.json",
"cves_map": {
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{
"id": "CVE-2020-8492",
"severity": [
{
"type": "CVSS_V3",
"score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H"
},
{
"type": "CVSS_V3",
"score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H"
},
{
"type": "Ubuntu",
"score": "low"
}
]
},
{
"id": "CVE-2021-3733",
"severity": [
{
"type": "CVSS_V3",
"score": "CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H"
},
{
"type": "Ubuntu",
"score": "medium"
}
]
},
{
"id": "CVE-2021-3737",
"severity": [
{
"type": "CVSS_V3",
"score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H"
},
{
"type": "CVSS_V3",
"score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H"
},
{
"type": "Ubuntu",
"score": "medium"
}
]
}
],
"ecosystem": "Ubuntu:18.04:LTS"
}
},
"ecosystem_specific": {
"binaries": [
{
"binary_name": "idle-python3.7",
"binary_version": "3.7.5-2ubuntu1~18.04.2"
},
{
"binary_name": "libpython3.7",
"binary_version": "3.7.5-2ubuntu1~18.04.2"
},
{
"binary_name": "libpython3.7-minimal",
"binary_version": "3.7.5-2ubuntu1~18.04.2"
},
{
"binary_name": "libpython3.7-stdlib",
"binary_version": "3.7.5-2ubuntu1~18.04.2"
},
{
"binary_name": "libpython3.7-testsuite",
"binary_version": "3.7.5-2ubuntu1~18.04.2"
},
{
"binary_name": "python3.7",
"binary_version": "3.7.5-2ubuntu1~18.04.2"
},
{
"binary_name": "python3.7-examples",
"binary_version": "3.7.5-2ubuntu1~18.04.2"
},
{
"binary_name": "python3.7-minimal",
"binary_version": "3.7.5-2ubuntu1~18.04.2"
},
{
"binary_name": "python3.7-venv",
"binary_version": "3.7.5-2ubuntu1~18.04.2"
}
],
"availability": "No subscription required"
}
},
{
"ranges": [
{
"type": "ECOSYSTEM",
"events": [
{
"introduced": "0"
},
{
"fixed": "3.8.0-3ubuntu1~18.04.2"
}
]
}
],
"package": {
"name": "python3.8",
"purl": "pkg:deb/ubuntu/python3.8?arch=source&distro=bionic",
"ecosystem": "Ubuntu:18.04:LTS"
},
"versions": [
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{
"type": "CVSS_V3",
"score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H"
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{
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},
{
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},
{
"type": "CVSS_V3",
"score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H"
},
{
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}
]
}
],
"ecosystem": "Ubuntu:18.04:LTS"
}
},
"ecosystem_specific": {
"binaries": [
{
"binary_name": "idle-python3.8",
"binary_version": "3.8.0-3ubuntu1~18.04.2"
},
{
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"binary_version": "3.8.0-3ubuntu1~18.04.2"
},
{
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{
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},
{
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"availability": "No subscription required"
}
}
],
"modified": "2026-10-08T19:46:32.340367978Z",
"provider": "osv",
"upstream": [
"CVE-2020-8492",
"CVE-2021-3733",
"CVE-2021-3737",
"UBUNTU-CVE-2020-8492",
"UBUNTU-CVE-2021-3733",
"UBUNTU-CVE-2021-3737"
],
"references": [
"https://ubuntu.com/security/notices/USN-5200-1",
"https://ubuntu.com/security/CVE-2020-8492",
"https://ubuntu.com/security/CVE-2021-3733",
"https://ubuntu.com/security/CVE-2021-3737"
]
},
"related_cves": [
{
"value": "CVE-2020-8492",
"evidence": "/upstream"
},
{
"value": "CVE-2021-3733",
"evidence": "/upstream"
},
{
"value": "CVE-2021-3737",
"evidence": "/upstream"
}
],
"security_relevant": true,
"severity_evidence": null
},
"source_id": "core-osv",
"document_id": 104518,
"published_at": "2021-12-17T14:59:29+00:00"
}