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Fencer Vulns
medium 6.5

CVE-2020-26137 json

CRLF injection in urllib3

published 2020-09-29 6 y ago modified 2026-06-17 4 mo ago also GHSA-wqvq-5m8c-6g24 , PYSEC-2020-148 , EUVD-2020-0230

cvss
6.5
version 3.1, NVD
cisa kev
Not listed
not in CISA's catalog
epss
2.3%
EPSS 2.3% chance of exploitation in 30 days, percentile 83%
public exploits
0
none known

Summary

urllib3 before 1.25.9 allows CRLF injection if the attacker controls the HTTP request method, as demonstrated by inserting CR and LF control characters in the first argument of putrequest(). NOTE: this is similar to CVE-2020-26116.

Patch / fix

  • pypi urllib3 1.25.9
  • python urllib3 1.25.9
  • python-urllib3 Debian 14, Debian 13, Debian 12 1.25.9-1

debian advisories DEBIAN-CVE-2020-26137

  • python-pip Ubuntu 16.04 LTS 8.1.1-2ubuntu0.6
  • python-pip Ubuntu 18.04 LTS 9.0.1-2.3~ubuntu1.18.04.3
  • python-pip Ubuntu 20.04 LTS 20.0.2-5ubuntu1.1
  • python-urllib3 Ubuntu 16.04 LTS 1.13.1-2ubuntu0.16.04.4
  • python-urllib3 Ubuntu 18.04 LTS 1.22-1ubuntu0.18.04.2
  • python-urllib3 Ubuntu 20.04 LTS 1.25.8-2ubuntu0.1

ubuntu advisories UBUNTU-CVE-2020-26137

Ubuntu security data © Canonical Ltd., from https://github.com/canonical/ubuntu-security-notices via OSV; changed: normalised to fixed package versions per release. CC BY-SA 4.0

  • python RHEL 7 2.7.5-92.el7_9
  • tkinter RHEL 7 2.7.5-92.el7_9
  • python-libs RHEL 7 2.7.5-92.el7_9
  • python-test RHEL 7 2.7.5-92.el7_9
  • python-tools RHEL 7 2.7.5-92.el7_9
  • python-urllib3 RHEL 8 1.24.2-5.el8
  • python3-urllib3 RHEL 8 1.24.2-5.el8
  • pytz RHEL 8 2017.2-12.module+el8.1.0+3111+de3f2d8e

red hat advisories RHSA-2022:5235RHSA-2021:1631RHSA-2021:1761RHSA-2021:0079RHSA-2021:0034RHSA-2020:4299

  • python-urllib3 SLES for SAP 12 SP5, SLES for SAP 12 SP4, SLES for SAP 12 SP3 +13 more 1.25.10-3.31.2
  • python-urllib3 SLES for SAP 15 SP1, SLES 15 SP1-LTSS, SLES 15 SP1-BCL +10 more 1.25.10-9.14.1
  • aws-cli SLE Module for Public Cloud 15 SP3, SLE Module for Public Cloud 15 SP2, SLE Module for Public Cloud 15 SP1 1.19.9-26.1
  • python-cffi SLE Module for Python 2 15 SP3, SLE Module for Python 2 15 SP2, SLE Module for Basesystem 15 SP3 +2 more 1.13.2-3.2.5
  • python-boto3 SLES for SAP 15 SP1, SLES 15 SP1-LTSS, SLES 15 SP1-BCL +10 more 1.17.9-19.1
  • python-pyasn1 SLES for SAP 15 SP1, SLES 15 SP1-LTSS, SLES 15 SP1-BCL +11 more 0.4.2-3.2.1
  • python-trustme SLE Module for Public Cloud 15 SP1 0.6.0-3.3.1
  • python-botocore SLES for SAP 15 SP1, SLES 15 SP1-LTSS, SLES 15 SP1-BCL +11 more 1.20.9-33.1

suse advisories SUSE-SU-2021:3251-1SUSE-SU-2021:2817-1SUSE-SU-2020:3897-1SUSE-SU-2020:3723-1SUSE-SU-2020:3624-1SUSE-SU-2020:3309-1

  • python-urllib3 openSUSE Tumbleweed 2.8.0-1.1
  • python-urllib3_1 openSUSE Tumbleweed 1.26.20-7.2
  • python-urllib3 openSUSE Tumbleweed 2.0.4-2.1
  • python-cffi openSUSE Leap 15.2 1.13.2-lp152.2.3.1
  • python-pyOpenSSL openSUSE Leap 15.2 17.5.0-lp152.7.3.1
  • python-cryptography openSUSE Leap 15.2 2.8-lp152.2.12.1
  • python-urllib3 openSUSE Leap 15.3 1.25.10-9.14.1
  • aws-cli openSUSE Leap 15.3 1.19.9-26.1

opensuse advisories openSUSE-SU-2026:12044-1openSUSE-SU-2026:12045-1openSUSE-SU-2024:13212-1openSUSE-SU-2021:1206-1openSUSE-SU-2021:2817-1openSUSE-SU-2020:2282-1

  • python2-py AlmaLinux 8 1.5.3-6.module_el8.6.0+2781+fed64c13
  • python2-dns AlmaLinux 8 1.15.0-10.module_el8.6.0+2781+fed64c13
  • python2-six AlmaLinux 8 1.11.0-6.module_el8.6.0+2781+fed64c13
  • python2-idna AlmaLinux 8 2.5-7.module_el8.6.0+2781+fed64c13
  • python2-mock AlmaLinux 8 2.0.0-13.module_el8.6.0+2781+fed64c13
  • python2-pytz AlmaLinux 8 2017.2-12.module_el8.6.0+2781+fed64c13
  • python2-attrs AlmaLinux 8 17.4.0-10.module_el8.6.0+2781+fed64c13
  • python2-numpy AlmaLinux 8 1:1.14.2-16.module_el8.6.0+2781+fed64c13

almalinux advisories ALSA-2021:1761ALSA-2021:1631

  • pytz Rocky Linux 8 2017.2-12.module+el8.5.0+706+735ec4b3
  • pytz Rocky Linux 8 2017.2-12.module+el8.4.0+403+9ae17a31
  • babel Rocky Linux 8 2.5.1-9.module+el8.4.0+403+9ae17a31
  • numpy Rocky Linux 8 1:1.14.2-16.module+el8.5.0+706+735ec4b3
  • numpy Rocky Linux 8 1:1.14.2-16.module+el8.4.0+403+9ae17a31
  • scipy Rocky Linux 8 1.0.0-20.module+el8.3.0+120+426d8baf
  • Cython Rocky Linux 8 0.28.1-7.module+el8.5.0+706+735ec4b3
  • Cython Rocky Linux 8 0.28.1-7.module+el8.4.0+403+9ae17a31

rocky linux advisories RLSA-2021:1761RLSA-2021:1631

  • py3-urllib3 Alpine 3.24, Alpine 3.23, Alpine 3.22 +9 more 1.25.9-r0

alpine advisories ALPINE-CVE-2020-26137

Alpine secdb © Alpine Linux, from https://secdb.alpinelinux.org via OSV; changed: normalised to fixed package versions per release. CC BY-SA 4.0

Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2020-26137 updated cvss 6.5

python-urllib3: CRLF injection via HTTP request method

  • Red Hat Enterprise Linux 6 python-urllib3 Red Hat OpenStack Platform 10 (Newton) python-urllib3
    affected: no fix planned “Out of support scope”
  • Red Hat OpenStack Platform 13 (Queens) python2-urllib3 Red Hat Software Collections rh-mongodb36-python-urllib3 Red Hat Storage 3 python-urllib3, python2-urllib3
    affected: no fix planned “Will not fix”
  • Red Hat Enterprise Linux AppStream (v. 8) babel 2.5.1-9.module+el8.1.0+3111+de3f2d8e, pytz 2017.2-12.module+el8.1.0+3111+de3f2d8e, PyYAML 3.12-16.module+el8.1.0+3111+de3f2d8e, scipy 1.0.0-20.module+el8.1.0+3323+7ac3e00f, Cython 0.28.1-7.module+el8.1.0+3111+de3f2d8e, numpy 1.14.2-16.module+el8.4.0+9406+221a4565, +83 more
    fixed: vendor fix RHSA-2021:1761
  • Red Hat Enterprise Linux BaseOS (v. 8) python-urllib3 1.24.2-5.el8, python3-urllib3 1.24.2-5.el8
    fixed: vendor fix RHSA-2021:1631
  • Red Hat Enterprise Linux Client (v. 7) python 2.7.5-92.el7_9, python-libs 2.7.5-92.el7_9 Red Hat Enterprise Linux Client Optional (v. 7) tkinter 2.7.5-92.el7_9, python-test 2.7.5-92.el7_9, python-tools 2.7.5-92.el7_9 Red Hat Enterprise Linux ComputeNode Optional (v. 7) tkinter 2.7.5-92.el7_9, python-test 2.7.5-92.el7_9, python-tools 2.7.5-92.el7_9 Red Hat Enterprise Linux Server (v. 7) python 2.7.5-92.el7_9, python-libs 2.7.5-92.el7_9 Red Hat Enterprise Linux Server Optional (v. 7) tkinter 2.7.5-92.el7_9, python-test 2.7.5-92.el7_9, python-tools 2.7.5-92.el7_9 Red Hat Enterprise Linux Workstation (v. 7) python 2.7.5-92.el7_9, python-libs 2.7.5-92.el7_9
    +1 more products
    Red Hat Enterprise Linux Workstation Optional (v. 7) tkinter 2.7.5-92.el7_9, python-test 2.7.5-92.el7_9, python-tools 2.7.5-92.el7_9
    fixed: vendor fix RHSA-2022:5235
  • Red Hat OpenShift Container Platform 3.11 python-urllib3 1.26.2-1.el7, python2-urllib3 1.26.2-1.el7
    fixed: vendor fix RHSA-2021:0079
  • Red Hat OpenShift Container Platform 4.5 python-urllib3 1.26.2-1.el7, python2-urllib3 1.26.2-1.el7
    fixed: vendor fix RHSA-2021:0034
  • Red Hat Software Collections for Red Hat Enterprise Linux Server (v. 7) rh-python38-python 3.8.6-1.el7, rh-python38-python-idle 3.8.6-1.el7, rh-python38-python-libs 3.8.6-1.el7, rh-python38-python-test 3.8.6-1.el7, rh-python38-python-psutil 5.6.4-5.el7, rh-python38-python-tkinter 3.8.6-1.el7, +3 more Red Hat Software Collections for Red Hat Enterprise Linux Server EUS (v. 7.6) rh-python38-python 3.8.6-1.el7, rh-python38-python-idle 3.8.6-1.el7, rh-python38-python-libs 3.8.6-1.el7, rh-python38-python-test 3.8.6-1.el7, rh-python38-python-psutil 5.6.4-5.el7, rh-python38-python-tkinter 3.8.6-1.el7, +3 more Red Hat Software Collections for Red Hat Enterprise Linux Server EUS (v. 7.7) rh-python38-python 3.8.6-1.el7, rh-python38-python-idle 3.8.6-1.el7, rh-python38-python-libs 3.8.6-1.el7, rh-python38-python-test 3.8.6-1.el7, rh-python38-python-psutil 5.6.4-5.el7, rh-python38-python-tkinter 3.8.6-1.el7, +3 more Red Hat Software Collections for Red Hat Enterprise Linux Workstation (v. 7) rh-python38-python 3.8.6-1.el7, rh-python38-python-idle 3.8.6-1.el7, rh-python38-python-libs 3.8.6-1.el7, rh-python38-python-test 3.8.6-1.el7, rh-python38-python-psutil 5.6.4-5.el7, rh-python38-python-tkinter 3.8.6-1.el7, +3 more
    fixed: vendor fix RHSA-2020:4299
show 1 more
  • Red Hat Enterprise Linux 7 python-pip, python3-pip Red Hat Enterprise Linux 8 python-pip, python3-pip, python38-pip, python39-pip, python3x-pip, python-urllib3, +5 more Red Hat OpenShift Container Platform 3.11 prometheus 3.11.374-1.git.5026.29379c4.el7, atomic-openshift 3.11.374-1.git.0.ebd3ee9.el7, openshift-ansible 3.11.374-1.git.0.92f5956.el7, openshift-kuryr 3.11.374-1.git.1478.ef11824.el7, atomic-openshift-pod 3.11.374-1.git.0.ebd3ee9.el7, atomic-openshift-node 3.11.374-1.git.0.ebd3ee9.el7, +34 more Red Hat OpenShift Container Platform 4.5 cri-o 1.18.4-5.rhaos4.5.gitd655863.el7, cri-o 1.18.4-5.rhaos4.5.gitd655863.el8, jenkins-2-plugins 4.5.1610108899-1.el7, openshift 4.5.0-202012221738.p0.git.0.9c544e4.el7, openshift 4.5.0-202012221738.p0.git.0.9c544e4.el8, openshift-kuryr 4.5.0-202012221738.p0.git.2004.e3caa5a.el8, +7 more Red Hat Software Collections python27-python-pip, rh-python36-python-pip, rh-python38-python-pip, rh-python38-python-pip-wheel
    not affected: vulnerable code not present

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

Exploit prediction

2.27% chance of exploitation in the next 30 days, higher than 83% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by version score vector
NVD 3.1 6.5 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N
NVD 2.0 6.4 AV:N/AC:L/Au:N/C:P/I:P/A:N
GitHub 3.1 6.5 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N

Affected packages

ecosystem package affected fixed in
pypi urllib3
<1.25.9
1.25.9

Classification

Weakness
  • CWE-74 Improper Neutralization of Special Elements in Output Used by a Downstream Component

References

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.