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CVE-2021-3737· NVD / CVE Program· CNA redhat

A flaw was found in python.

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.

HighCVSS 7.5 · v3.1—No exploit Fix available
Published
Mar 4, 2022
Updated
Jun 17, 2026
EPSS
11.6% · 96th percentile
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Report tools

JSON

Action score

33

Monitor

Low priority for now.

CVSS
30 / 40 · 7.5 / 10
CISA KEV
0 / 30 · Not listed
EPSS
3 / 30 · 11.6%

CISA SSVC decision

Exploitation
none
Automatable
yes
Technical impact
partial

Vulnrichment: CISA's decision-tree inputs.

Noroxi analysis

No Noroxi analysis for this record yet

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Affected systems

VendorProduct
pythonpython
redhatcodeready linux builder
redhatcodeready linux builder for ibm z systems
redhatcodeready linux builder for power little endian
redhatenterprise linux
redhatenterprise linux for ibm z systems
redhatenterprise linux for power little endian
fedoraprojectfedora
canonicalubuntu linux
netapphci
netappmanagement services for element software
netappnetapp xcp smb

and 5 more

Affected versions

NVD version ranges (for catalog products). Add the product to your stack with a version and matching uses these.

  • canonical ubuntu linux14.04
  • canonical ubuntu linux16.04
  • canonical ubuntu linux18.04
  • canonical ubuntu linux20.04
  • canonical ubuntu linux21.04
  • fedoraproject fedora33
  • fedoraproject fedora34
  • netapp hciall versions
  • netapp management services for element softwareall versions
  • netapp netapp xcp smball versions
  • netapp ontap select deploy administration utilityall versions
  • netapp xcp nfsall versions
  • oracle communications cloud native core binding support function22.1.3
  • oracle communications cloud native core network exposure function22.1.1
  • oracle communications cloud native core policy22.2.0
  • python python3.6.0 and later · before 3.6.14
  • python python3.7.0 and later · before 3.7.11
  • python python3.8.0 and later · before 3.8.11
  • python python3.9.0 and later · before 3.9.6
  • redhat codeready linux builder8.0

Versions reported by the vendor

Affected version ranges reported by the assigning authority (redhat). Independent of NVD's CPE analysis and usually ahead of it.

  • n/a python

    • Fixed in python v3.6.14, python v3.7.11, python v3.8.11, python v3.9.6, python v3.10.0b2affected

Package-level exposure

OSV and GitHub Advisory data: ecosystem, package and range. SBOM matching uses this table.

EcosystemPackageAffected rangeFix
AlmaLinux:8babelbefore 2.5.1-10.module_el8.6.0+2781+fed64c132.5.1-10.module_el8.6.0+2781+fed64c13
AlmaLinux:8platform-pythonbefore 3.6.8-45.el8.alma3.6.8-45.el8.alma
AlmaLinux:8platform-python-debugbefore 3.6.8-45.el8.alma3.6.8-45.el8.alma
AlmaLinux:8platform-python-develbefore 3.6.8-45.el8.alma3.6.8-45.el8.alma
AlmaLinux:8python-nose-docsbefore 1.3.7-31.module_el8.5.0+2569+5c5719bc1.3.7-31.module_el8.5.0+2569+5c5719bc
AlmaLinux:8python-nose-docsbefore 1.3.7-31.module_el8.6.0+2781+fed64c131.3.7-31.module_el8.6.0+2781+fed64c13
AlmaLinux:8python-psycopg2-docbefore 2.7.5-7.module_el8.6.0+2781+fed64c132.7.5-7.module_el8.6.0+2781+fed64c13
AlmaLinux:8python-sqlalchemy-docbefore 1.3.2-2.module_el8.5.0+2569+5c5719bc1.3.2-2.module_el8.5.0+2569+5c5719bc
AlmaLinux:8python-sqlalchemy-docbefore 1.3.2-2.module_el8.6.0+2781+fed64c131.3.2-2.module_el8.6.0+2781+fed64c13
AlmaLinux:8python2before 2.7.18-10.module_el8.6.0+2781+fed64c13.alma2.7.18-10.module_el8.6.0+2781+fed64c13.alma
AlmaLinux:8python2-attrsbefore 17.4.0-10.module_el8.6.0+2781+fed64c1317.4.0-10.module_el8.6.0+2781+fed64c13
AlmaLinux:8python2-babelbefore 2.5.1-10.module_el8.6.0+2781+fed64c132.5.1-10.module_el8.6.0+2781+fed64c13
AlmaLinux:8python2-backportsbefore 1.0-16.module_el8.6.0+2781+fed64c131.0-16.module_el8.6.0+2781+fed64c13
AlmaLinux:8python2-backports-ssl_match_hostnamebefore 3.5.0.1-12.module_el8.6.0+2781+fed64c133.5.0.1-12.module_el8.6.0+2781+fed64c13
AlmaLinux:8python2-bsonbefore 3.7.0-1.module_el8.6.0+2781+fed64c133.7.0-1.module_el8.6.0+2781+fed64c13
AlmaLinux:8python2-chardetbefore 3.0.4-10.module_el8.6.0+2781+fed64c133.0.4-10.module_el8.6.0+2781+fed64c13
AlmaLinux:8python2-coveragebefore 4.5.1-4.module_el8.6.0+2781+fed64c134.5.1-4.module_el8.6.0+2781+fed64c13
AlmaLinux:8python2-Cythonbefore 0.28.1-7.module_el8.6.0+2781+fed64c130.28.1-7.module_el8.6.0+2781+fed64c13
AlmaLinux:8python2-debugbefore 2.7.18-10.module_el8.6.0+2781+fed64c13.alma2.7.18-10.module_el8.6.0+2781+fed64c13.alma
AlmaLinux:8python2-develbefore 2.7.18-10.module_el8.6.0+2781+fed64c13.alma2.7.18-10.module_el8.6.0+2781+fed64c13.alma
AlmaLinux:8python2-dnsbefore 1.15.0-10.module_el8.6.0+2781+fed64c131.15.0-10.module_el8.6.0+2781+fed64c13
AlmaLinux:8python2-docsbefore 2.7.16-2.module_el8.6.0+2781+fed64c132.7.16-2.module_el8.6.0+2781+fed64c13
AlmaLinux:8python2-docs-infobefore 2.7.16-2.module_el8.6.0+2781+fed64c132.7.16-2.module_el8.6.0+2781+fed64c13
AlmaLinux:8python2-docutilsbefore 0.14-12.module_el8.6.0+2781+fed64c130.14-12.module_el8.6.0+2781+fed64c13

+96

Other highest-scoring records for the same primary product.

  • CVE-2016-5636Integer overflow in the get_data function in zipimport.c in CPython (aka Python) before 2.7.12, 3.x before 3.4.5, and 3.5.x before 3.5.2 all
    47Plan
  • CVE-2007-4559Directory traversal vulnerability in the (1) extract and (2) extractall functions in the tarfile module in Python allows user-assisted remot
    47Plan
  • CVE-2021-3177Python 3.x through 3.9.1 has a buffer overflow in PyCArg_repr in _ctypes/callproc.c, which may lead to remote code execution in certain Pyth
    46Plan
  • CVE-2014-4650The CGIHTTPServer module in Python 2.7.5 and 3.3.4 does not properly handle URLs in which URL encoding is used for path separators, which al
    46Plan
  • CVE-2018-1000802Python Software Foundation Python (CPython) version 2.7 contains a CWE-77: Improper Neutralization of Special Elements used in a Command ('C
    45Plan
  • CVE-2020-27619In Python 3 through 3.9.0, the Lib/test/multibytecodec_support.py CJK codec tests call eval() on content retrieved via HTTP.
    42Plan

Remediation

Which version to upgrade to

Fix versions compiled from the vendor, package registries and Microsoft. Verify the vendor's note before upgrading.

Product / packageFixed versionSource
almalinux:python39-attrs20.3.0-2.module_el8.6.0+2780+a40f65e1 · AlmaLinux:8Package registry (OSV)
almalinux:python39-cffi1.14.3-2.module_el8.6.0+2780+a40f65e1 · AlmaLinux:8Package registry (OSV)
almalinux:python39-chardet3.0.4-19.module_el8.6.0+2780+a40f65e1 · AlmaLinux:8Package registry (OSV)
almalinux:python39-cryptography3.3.1-2.module_el8.6.0+2780+a40f65e1 · AlmaLinux:8Package registry (OSV)
almalinux:python39-Cython0.29.21-5.module_el8.6.0+2780+a40f65e1 · AlmaLinux:8Package registry (OSV)
almalinux:python39-idna2.10-3.module_el8.6.0+2780+a40f65e1 · AlmaLinux:8Package registry (OSV)
almalinux:python39-iniconfig1.1.1-2.module_el8.6.0+2780+a40f65e1 · AlmaLinux:8Package registry (OSV)
almalinux:python39-mod_wsgi4.7.1-4.module_el8.6.0+2780+a40f65e1 · AlmaLinux:8Package registry (OSV)
almalinux:python39-more-itertools8.5.0-2.module_el8.6.0+2780+a40f65e1 · AlmaLinux:8Package registry (OSV)
almalinux:python39-numpy1.19.4-3.module_el8.6.0+2780+a40f65e1 · AlmaLinux:8Package registry (OSV)
almalinux:python39-numpy-doc1.19.4-3.module_el8.6.0+2780+a40f65e1 · AlmaLinux:8Package registry (OSV)
almalinux:python39-PyMySQL0.10.1-2.module_el8.6.0+2780+a40f65e1 · AlmaLinux:8Package registry (OSV)
debian:pypy37.3.8+dfsg-1 · Debian:12Package registry (OSV)
debian:python2.72.7.16-2+deb10u2 · Debian:10Package registry (OSV)
debian:python3.53.5.3-1+deb9u5 · Debian:9Package registry (OSV)
debian:python3.73.7.3-2+deb10u5 · Debian:10Package registry (OSV)
debian:python3.93.9.2-1+deb11u2 · Debian:11Package registry (OSV)
opensuse:python2.7.18-lp152.3.21.1 · openSUSE:Leap 15.2Package registry (OSV)
opensuse:python-base2.7.18-lp152.3.21.1 · openSUSE:Leap 15.2Package registry (OSV)
opensuse:python-doc2.7.18-lp152.3.21.1 · openSUSE:Leap 15.2Package registry (OSV)
opensuse:python33.6.15-10.9.1 · openSUSE:Leap 15.3Package registry (OSV)
opensuse:python3-core3.6.15-10.9.1 · openSUSE:Leap 15.3Package registry (OSV)
opensuse:python3-documentation3.6.15-10.9.1 · openSUSE:Leap 15.3Package registry (OSV)
opensuse:python393.9.10-150300.4.8.2 · openSUSE:Leap 15.3Package registry (OSV)
opensuse:python39-core3.9.10-150300.4.8.1 · openSUSE:Leap 15.3Package registry (OSV)
opensuse:python39-documentation3.9.10-150300.4.8.1 · openSUSE:Leap 15.3Package registry (OSV)
red hat:mod_wsgi0:4.7.1-4.module+el8.4.0+9822+20bf1249 · Red Hat:enterprise_linux:8::appstreamPackage registry (OSV)
red hat:numpy0:1.19.4-3.module+el8.5.0+12204+54860423 · Red Hat:enterprise_linux:8::appstreamPackage registry (OSV)
red hat:numpy-debugsource0:1.19.4-3.module+el8.5.0+12204+54860423 · Red Hat:enterprise_linux:8::appstreamPackage registry (OSV)
red hat:python-cffi0:1.14.3-2.module+el8.4.0+9822+20bf1249 · Red Hat:enterprise_linux:8::appstreamPackage registry (OSV)

+30

Exploit status

No known public exploit

No public exploit has been observed yet. That doesn't mean you're safe, only that the bar is a little higher.

Research context

For pentesters and researchers: attack profile, score disagreement, timeline, patch commits, credits, variant and chain candidates, bug bounty scope. All derived from existing data; no exploit code.

Timeline

From publication to today: proof of concept, Metasploit module, CISA KEV and fix record. Dates are as reported by the sources.

No dated events beyond publication.

EPSS, last 120 days

FIRST EPSS daily score; only changes of 0.01 or more are recorded (step chart).

Patch and commit links

Commit, PR and diff links among the references. A starting point for patch-diffing and variant hunting; fixes, not exploits.

Finders, reporters and analysts named in the CNA record. Click a name for that researcher’s other records.

No credits in the CNA record.

Variant candidates

Same product, same weakness class, within 18 months. If the patch missed the root cause, the sibling bug is here.

No nightly-computed relations.

Chain candidates

An authentication bypass and a privilege-requiring bug in the same product, published close together: combined they may become an unauthenticated path.

—

Bug bounty scope

No known public program.

Source: bounty-targets-data (public HackerOne, Bugcrowd, Intigriti, YesWeHack listings).

Technical details

Attack conditions

  • Anyone who can reach it over the internet can trigger it.
  • No account or password is required.
  • No user action is required.
  • No special conditions are required; it is repeatable.

If successful

Confidentiality
none
Integrity
none
Availability
high · the service can be disrupted
Attack vector
Network
Attack complexity
Low
Privileges required
None
User interaction
None
Scope
Unchanged
Confidentiality impact
None
Integrity impact
None
Availability impact
High

CVSS vector

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

nvd-primary

Attack context

MITRE CAPEC attack patterns and ATT&CK techniques for this weakness class (CWE). A starting point for detection rules and threat hunting.

MITRE has no CAPEC/ATT&CK mapping for this CWE.

Change log

  1. Fix✗ → ✓

For records you follow, these changes also arrive as notifications. →

References

All records