High
Security advisory
A flaw was found in python. An improperly handled HTTP response in the HTTP client code of python may allow a remote attacker, who controls the HTTP server, to make the client script enter an infinite loop, consuming CPU time. The highest threat from this vulnerability is to system availability.
- Products
- Not specified
- Affected versions
- Not specified
- Fixed versions
- Not specified
- CVEs
- CVE-2021-3737
- Confirmed fixed CVEs
- Not specified
- Updated in this feed
- 31 Oct 2026, 11:50 UTC · Revision 1
Source evidence
A flaw was found in python. An improperly handled HTTP response in the HTTP client code of python may allow a remote attacker, who controls the HTTP server, to make the client script enter an infinite loop, consuming CPU time. The highest threat from this vulnerability is to system availability.
osv:CVE-2021-3737
Complete source record
{
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"url": "https://osv.dev/vulnerability/CVE-2021-3737",
"method": "structured",
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"title": "CVE-2021-3737",
"summary": "A flaw was found in python. An improperly handled HTTP response in the HTTP client code of python may allow a remote attacker, who controls the HTTP server, to make the client script enter an infinite loop, consuming CPU time. The highest threat from this vulnerability is to system availability.",
"evidence": "osv:CVE-2021-3737",
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"modified": "2026-10-20T10:54:49.218214938Z",
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"https://lists.debian.org/debian-lts-announce/2023/05/msg00024.html",
"https://lists.debian.org/debian-lts-announce/2023/06/msg00039.html",
"https://lists.debian.org/debian-lts-announce/2024/11/msg00024.html",
"https://lists.debian.org/debian-lts-announce/2024/12/msg00000.html",
"https://security.netapp.com/advisory/ntap-20220407-0009/",
"https://bugs.python.org/issue44022",
"https://bugzilla.redhat.com/show_bug.cgi?id=1995162",
"https://github.com/python/cpython/pull/25916",
"https://github.com/python/cpython/pull/26503",
"https://python-security.readthedocs.io/vuln/urllib-100-continue-loop.html",
"https://ubuntu.com/security/CVE-2021-3737",
"https://www.oracle.com/security-alerts/cpujul2022.html"
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"source_id": "core-osv",
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"published_at": "2022-03-04T19:15:08.73+00:00"
}