CVE-2021-3737

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Summary

CVECVE-2021-3737
StatePUBLISHED
Assignerredhat
Source PriorityCVE Program / NVD first with legacy fallback
Published2022-03-04 19:15:08 UTC
Updated2026-10-14 10:17:47 UTC
DescriptionA 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.

Risk And Classification

Primary CVSS: v3.1 7.5 HIGH from [email protected]

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Problem Types: CWE-835 | CWE-400 | CWE-835 CWE-835 - Loop with Unreachable Exit Condition ('Infinite Loop'), CWE-400 - Uncontrolled Resource Consumption

VersionSourceTypeScoreSeverityVector
3.1[email protected]Primary7.5HIGHCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
3.1ADPDECLARED7.5HIGHCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
3.1134c704f-9b21-4f2e-91b3-4a467353bcc0Secondary7.5HIGHCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
2.0[email protected]Primary7.1AV:N/AC:M/Au:N/C:N/I:N/A:C

CVSS v3.1 Breakdown

Attack Vector
Network
Attack Complexity
Low
Privileges Required
None
User Interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
None
Availability
High

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

CVSS v2.0 Breakdown

Access Vector
Network
Access Complexity
Medium
Authentication
None
Confidentiality
None
Integrity
None
Availability
Complete

AV:N/AC:M/Au:N/C:N/I:N/A:C

NVD Known Affected Configurations (CPE 2.3)

TypeVendorProductVersionUpdateEditionLanguage
Application Python Python All All All All

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Na Python affected Fixed in python v3.6.14, python v3.7.11, python v3.8.11, python v3.9.6, python v3.10.0b2 Not specified
ADP Siemens SIMATIC S7-1500 CPU 1518-4 PN/DP MFP affected V3.1.0 V3.1.5 custom Not specified
ADP Siemens SIMATIC S7-1500 CPU 1518-4 PN/DP MFP affected V3.1.0 V3.1.5 custom Not specified
ADP Siemens SIMATIC S7-1500 CPU 1518F-4 PN/DP MFP affected V3.1.0 V3.1.5 custom Not specified
ADP Siemens SIMATIC S7-1500 CPU 1518F-4 PN/DP MFP affected V3.1.0 V3.1.5 custom Not specified
ADP Siemens SIPLUS S7-1500 CPU 1518-4 PN/DP MFP affected V3.1.0 V3.1.5 custom Not specified

References

ReferenceSourceLinkTags
cert-portal.siemens.com/productcert/html/ssa-398330.html 0b142b55-0307-4c5a-b3c9-f314f3fb7c5e cert-portal.siemens.com
CVE-2021-3737 | Ubuntu af854a3a-2127-422b-91ae-364da2661108 ubuntu.com Patch, Third Party Advisory
Issue 44022: CVE-2021-3737: urllib http client possible infinite loop on a 100 Continue response - Python tracker af854a3a-2127-422b-91ae-364da2661108 bugs.python.org Exploit, Issue Tracking, Vendor Advisory
bpo-44022: Improve the security fix regression test. by gpshead · Pull Request #26503 · python/cpython · GitHub af854a3a-2127-422b-91ae-364da2661108 github.com Patch, Third Party Advisory
bpo-44022: Fix http client infinite line reading (DoS) after a http 100 by gen-xu · Pull Request #25916 · python/cpython · GitHub af854a3a-2127-422b-91ae-364da2661108 github.com Patch, Third Party Advisory
CVE-2021-3737: urllib HTTP client possible infinite loop on a 100 Continue response — Python Security 0.0 documentation af854a3a-2127-422b-91ae-364da2661108 python-security.readthedocs.io Patch, Third Party Advisory
1995162 – (CVE-2021-3737) CVE-2021-3737 python: urllib: HTTP client possible infinite loop on a 100 Continue response af854a3a-2127-422b-91ae-364da2661108 bugzilla.redhat.com Issue Tracking, Patch, Third Party Advisory
CVE-2021-3737 Python Vulnerability in NetApp Products | NetApp Product Security af854a3a-2127-422b-91ae-364da2661108 security.netapp.com Third Party Advisory
lists.debian.org/debian-lts-announce/2024/12/msg00000.html af854a3a-2127-422b-91ae-364da2661108 lists.debian.org
[SECURITY] [DLA 3477-1] python3.7 security update af854a3a-2127-422b-91ae-364da2661108 lists.debian.org
Oracle Critical Patch Update Advisory - July 2022 af854a3a-2127-422b-91ae-364da2661108 www.oracle.com Patch, Third Party Advisory
lists.debian.org/debian-lts-announce/2024/11/msg00024.html af854a3a-2127-422b-91ae-364da2661108 lists.debian.org
[SECURITY] [DLA 3432-1] python2.7 security update af854a3a-2127-422b-91ae-364da2661108 lists.debian.org
CVE Program record CVE.ORG www.cve.org canonical
NVD vulnerability detail NVD nvd.nist.gov canonical, analysis

Legacy QID Mappings

  • 159466 Oracle Enterprise Linux Security Update for python39:3.9 and python39-devel:3.9 (ELSA-2021-4160)
  • 159797 Oracle Enterprise Linux Security Update for python38:3.8 and python38-devel:3.8 (ELSA-2022-1764)
  • 159808 Oracle Enterprise Linux Security Update for python3 (ELSA-2022-1986)
  • 159819 Oracle Enterprise Linux Security Update for python27:2.7 (ELSA-2022-1821)
  • 178882 Debian Security Update for python3.5 (DLA 2808-1)
  • 181802 Debian Security Update for python2.7 (DLA 3432-1)
  • 198609 Ubuntu Security Notification for Python Vulnerabilities (USN-5199-1)
  • 198610 Ubuntu Security Notification for Python Vulnerabilities (USN-5201-1)
  • 198611 Ubuntu Security Notification for Python Vulnerabilities (USN-5200-1)
  • 20270 Oracle Database 21c Critical Patch Update - October 2022
  • 20317 Oracle Database 21c Critical Patch Update - January 2023
  • 239841 Red Hat Update for python39:3.9 and python39-devel:3.9 (RHSA-2021:4160)
  • 240254 Red Hat Update for python27-python and python27-python-pip (RHSA-2022:1663)
  • 240287 Red Hat Update for python38:3.8 and python38-devel:3.8 (RHSA-2022:1764)
  • 240302 Red Hat Update for python27:2.7 (RHSA-2022:1821)
  • 240313 Red Hat Update for python3 (RHSA-2022:1986)
  • 281936 Fedora Security Update for python2.7 (FEDORA-2021-34760089da)
  • 281937 Fedora Security Update for python2.7 (FEDORA-2021-68d0f3043a)
  • 281947 Fedora Security Update for mingw (FEDORA-2021-eef0654c0b)
  • 296062 Oracle Solaris 11.4 Support Repository Update (SRU) 43.113.3 Missing (CPUJAN2022)
  • 353942 Amazon Linux Security Advisory for python : ALAS2-2022-1802
  • 353955 Amazon Linux Security Advisory for python27 : ALAS-2022-1593
  • 6000019 Debian Security Update for python3.7 (DLA 3477-1)
  • 671034 EulerOS Security Update for python (EulerOS-SA-2021-2669)
  • 671148 EulerOS Security Update for python2 (EulerOS-SA-2021-2812)
  • 671155 EulerOS Security Update for python3 (EulerOS-SA-2021-2813)
  • 671213 EulerOS Security Update for python3 (EulerOS-SA-2022-1013)
  • 671224 EulerOS Security Update for python3 (EulerOS-SA-2022-1033)
  • 671253 EulerOS Security Update for python (EulerOS-SA-2022-1183)
  • 671296 EulerOS Security Update for python3 (EulerOS-SA-2022-1214)
  • 671306 EulerOS Security Update for python3 (EulerOS-SA-2022-1233)
  • 751252 SUSE Enterprise Linux Security Update for python3 (SUSE-SU-2021:3477-1)
  • 751261 SUSE Enterprise Linux Security Update for python36 (SUSE-SU-2021:3486-1)
  • 751268 OpenSUSE Security Update for python (openSUSE-SU-2021:3489-1)
  • 751274 SUSE Enterprise Linux Security Update for python (SUSE-SU-2021:3524-1)
  • 751306 OpenSUSE Security Update for python (openSUSE-SU-2021:1418-1)
  • 751494 OpenSUSE Security Update for python3 (openSUSE-SU-2021:4104-1)
  • 751548 SUSE Enterprise Linux Security Update for python3 (SUSE-SU-2021:4015-2)
  • 752098 SUSE Enterprise Linux Security Update for python39 (SUSE-SU-2022:1485-1)
  • 900745 Common Base Linux Mariner (CBL-Mariner) Security Update for python3 (8956)
  • 940499 AlmaLinux Security Update for python27:2.7 (ALSA-2022:1821)
  • 940530 AlmaLinux Security Update for python3 (ALSA-2022:1986)
  • 940557 AlmaLinux Security Update for python38:3.8 and python38-devel:3.8 (ALSA-2022:1764)
  • 940559 AlmaLinux Security Update for python39:3.9 and python39-devel:3.9 (ALSA-2021:4160)
  • 960239 Rocky Linux Security Update for python39:3.9 and python39-devel:3.9 (RLSA-2021:4160)
  • 960252 Rocky Linux Security Update for python38:3.8 and python38-devel:3.8 (RLSA-2022:1764)
  • 960259 Rocky Linux Security Update for python27:2.7 (RLSA-2022:1821)
  • 960408 Rocky Linux Security Update for python3 (RLSA-2022:1986)

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