CVE-2021-3737

  1. OpenCVE
  2. Vulnerabilities (CVE)
  3. CVE-2021-3737
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.

7.5 /10

CVSS v3 : HIGH

V3 Legend

Vector :

Exploitability : 3.9 / Impact : 3.6

Attack Vector NETWORK

Attack Complexity LOW

Privileges Required NONE

User Interaction NONE

Confidentiality Impact NONE

Integrity Impact NONE

Availability Impact HIGH

Scope UNCHANGED

7.1 /10

CVSS v2.0 : HIGH

V2 Legend

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

Exploitability : 8.6 / Impact : 6.9

Access Vector NETWORK

Access Complexity MEDIUM

Authentication NONE

Confidentiality Impact NONE

Integrity Impact NONE

Availability Impact COMPLETE

References
Link Resource
https://bugs.python.org/issue44022 Exploit Issue Tracking Vendor Advisory
https://bugzilla.redhat.com/show_bug.cgi?id=1995162 Issue Tracking Patch Third Party Advisory
https://github.com/python/cpython/pull/25916 Patch Third Party Advisory
https://github.com/python/cpython/pull/26503 Patch Third Party Advisory
https://lists.debian.org/debian-lts-announce/2023/05/msg00024.html
https://lists.debian.org/debian-lts-announce/2023/06/msg00039.html
https://python-security.readthedocs.io/vuln/urllib-100-continue-loop.html Patch Third Party Advisory
https://security.netapp.com/advisory/ntap-20220407-0009/ Third Party Advisory
https://ubuntu.com/security/CVE-2021-3737 Patch Third Party Advisory
https://www.oracle.com/security-alerts/cpujul2022.html Patch Third Party Advisory
https://bugs.python.org/issue44022 Exploit Issue Tracking Vendor Advisory
https://bugzilla.redhat.com/show_bug.cgi?id=1995162 Issue Tracking Patch Third Party Advisory
https://github.com/python/cpython/pull/25916 Patch Third Party Advisory
https://github.com/python/cpython/pull/26503 Patch Third Party Advisory
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://python-security.readthedocs.io/vuln/urllib-100-continue-loop.html Patch Third Party Advisory
https://security.netapp.com/advisory/ntap-20220407-0009/ Third Party Advisory
https://ubuntu.com/security/CVE-2021-3737 Patch Third Party Advisory
https://www.oracle.com/security-alerts/cpujul2022.html Patch Third Party Advisory
Configurations

Configuration 1 (hide)

OR cpe:2.3:a:python:python:*:*:*:*:*:*:*:*
cpe:2.3:a:python:python:*:*:*:*:*:*:*:*
cpe:2.3:a:python:python:*:*:*:*:*:*:*:*
cpe:2.3:a:python:python:*:*:*:*:*:*:*:*

Configuration 2 (hide)

OR cpe:2.3:a:redhat:codeready_linux_builder:8.0:*:*:*:*:*:*:*
cpe:2.3:a:redhat:codeready_linux_builder_for_ibm_z_systems:8.0:*:*:*:*:*:*:*
cpe:2.3:a:redhat:codeready_linux_builder_for_power_little_endian:8.0:*:*:*:*:*:*:*
cpe:2.3:o:redhat:enterprise_linux:6.0:*:*:*:*:*:*:*
cpe:2.3:o:redhat:enterprise_linux:7.0:*:*:*:*:*:*:*
cpe:2.3:o:redhat:enterprise_linux:8.0:*:*:*:*:*:*:*
cpe:2.3:o:redhat:enterprise_linux_for_ibm_z_systems:8.0:*:*:*:*:*:*:*
cpe:2.3:o:redhat:enterprise_linux_for_power_little_endian:8.0:*:*:*:*:*:*:*

Configuration 3 (hide)

OR cpe:2.3:o:fedoraproject:fedora:33:*:*:*:*:*:*:*
cpe:2.3:o:fedoraproject:fedora:34:*:*:*:*:*:*:*

Configuration 4 (hide)

OR cpe:2.3:o:canonical:ubuntu_linux:14.04:*:*:*:esm:*:*:*
cpe:2.3:o:canonical:ubuntu_linux:16.04:*:*:*:esm:*:*:*
cpe:2.3:o:canonical:ubuntu_linux:18.04:*:*:*:lts:*:*:*
cpe:2.3:o:canonical:ubuntu_linux:20.04:*:*:*:lts:*:*:*
cpe:2.3:o:canonical:ubuntu_linux:21.04:*:*:*:*:*:*:*

Configuration 5 (hide)

OR cpe:2.3:a:netapp:hci:-:*:*:*:*:*:*:*
cpe:2.3:a:netapp:management_services_for_element_software:-:*:*:*:*:*:*:*
cpe:2.3:a:netapp:netapp_xcp_smb:-:*:*:*:*:*:*:*
cpe:2.3:a:netapp:ontap_select_deploy_administration_utility:-:*:*:*:*:*:*:*
cpe:2.3:a:netapp:xcp_nfs:-:*:*:*:*:*:*:*

Configuration 6 (hide)

OR cpe:2.3:a:oracle:communications_cloud_native_core_binding_support_function:22.1.3:*:*:*:*:*:*:*
cpe:2.3:a:oracle:communications_cloud_native_core_network_exposure_function:22.1.1:*:*:*:*:*:*:*
cpe:2.3:a:oracle:communications_cloud_native_core_policy:22.2.0:*:*:*:*:*:*:*
History

03 Nov 2025, 22:15

Type Values Removed Values Added
References
  • () https://lists.debian.org/debian-lts-announce/2024/11/msg00024.html -
  • () https://lists.debian.org/debian-lts-announce/2024/12/msg00000.html -

21 Nov 2024, 06:22

Type Values Removed Values Added
References () https://bugs.python.org/issue44022 - Exploit, Issue Tracking, Vendor Advisory () https://bugs.python.org/issue44022 - Exploit, Issue Tracking, Vendor Advisory
References () https://bugzilla.redhat.com/show_bug.cgi?id=1995162 - Issue Tracking, Patch, Third Party Advisory () https://bugzilla.redhat.com/show_bug.cgi?id=1995162 - Issue Tracking, Patch, Third Party Advisory
References () https://github.com/python/cpython/pull/25916 - Patch, Third Party Advisory () https://github.com/python/cpython/pull/25916 - Patch, Third Party Advisory
References () https://github.com/python/cpython/pull/26503 - Patch, Third Party Advisory () https://github.com/python/cpython/pull/26503 - Patch, Third Party Advisory
References () https://lists.debian.org/debian-lts-announce/2023/05/msg00024.html - () https://lists.debian.org/debian-lts-announce/2023/05/msg00024.html -
References () https://lists.debian.org/debian-lts-announce/2023/06/msg00039.html - () https://lists.debian.org/debian-lts-announce/2023/06/msg00039.html -
References () https://python-security.readthedocs.io/vuln/urllib-100-continue-loop.html - Patch, Third Party Advisory () https://python-security.readthedocs.io/vuln/urllib-100-continue-loop.html - Patch, Third Party Advisory
References () https://security.netapp.com/advisory/ntap-20220407-0009/ - Third Party Advisory () https://security.netapp.com/advisory/ntap-20220407-0009/ - Third Party Advisory
References () https://ubuntu.com/security/CVE-2021-3737 - Patch, Third Party Advisory () https://ubuntu.com/security/CVE-2021-3737 - Patch, Third Party Advisory
References () https://www.oracle.com/security-alerts/cpujul2022.html - Patch, Third Party Advisory () https://www.oracle.com/security-alerts/cpujul2022.html - Patch, Third Party Advisory

30 Jun 2023, 23:15

Type Values Removed Values Added
References
  • (MLIST) https://lists.debian.org/debian-lts-announce/2023/06/msg00039.html -

24 May 2023, 21:15

Type Values Removed Values Added
References
  • (MLIST) https://lists.debian.org/debian-lts-announce/2023/05/msg00024.html -
Information

Published : 2022-03-04 19:15

Updated : 2025-11-03 22:15

NVD link : CVE-2021-3737

Mitre link : CVE-2021-3737

CVE.ORG link : CVE-2021-3737

JSON object : View

Products Affected

redhat

  • codeready_linux_builder
  • codeready_linux_builder_for_ibm_z_systems
  • enterprise_linux_for_ibm_z_systems
  • enterprise_linux
  • enterprise_linux_for_power_little_endian
  • codeready_linux_builder_for_power_little_endian

netapp

  • hci
  • ontap_select_deploy_administration_utility
  • xcp_nfs
  • netapp_xcp_smb
  • management_services_for_element_software

fedoraproject

  • fedora

canonical

  • ubuntu_linux

oracle

  • communications_cloud_native_core_binding_support_function
  • communications_cloud_native_core_network_exposure_function
  • communications_cloud_native_core_policy

python

  • python
CWE
CWE-835

Loop with Unreachable Exit Condition ('Infinite Loop')

CWE-400

Uncontrolled Resource Consumption