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Fencer Vulns
medium 6.5

CVE-2020-8492 json

Python 2.7 through 2.7.17, 3.5 through 3.5.9, 3.6 through 3.6.10, 3.7 through 3.7.6, and 3.8 through 3.8.1 allows an HTTP server to conduct…

published 2020-01-30 6 y ago modified 2026-10-14 26 d ago also BIT-libpython-2020-8492 , BIT-python-2020-8492 , BIT-python-min-2020-8492 , EUVD-2020-29358

cvss
6.5
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
6.6%
EPSS 6.6% chance of exploitation in 30 days, percentile 93%
public exploits
0
none known

Summary

Python 2.7 through 2.7.17, 3.5 through 3.5.9, 3.6 through 3.6.10, 3.7 through 3.7.6, and 3.8 through 3.8.1 allows an HTTP server to conduct Regular Expression Denial of Service (ReDoS) attacks against a client because of urllib.request.AbstractBasicAuthHandler catastrophic backtracking.

Patch / fix

  • bitnami libpython 2.7.18, 3.5.10, 3.6.11, 3.7.7, 3.8.2
  • bitnami python 2.7.18, 3.5.10, 3.6.11, 3.7.7, 3.8.2
  • bitnami python-min 2.7.18, 3.5.10, 3.6.11, 3.7.7, 3.8.2
  • Siemens SIMATIC S7-1500 CPU 1518-4 PN/DP MFP V3.1.5
  • Siemens SIMATIC S7-1500 CPU 1518F-4 PN/DP MFP V3.1.5
  • Siemens SIPLUS S7-1500 CPU 1518-4 PN/DP MFP V3.1.5
  • python2.7 Debian 11 2.7.18-2

debian advisories DEBIAN-CVE-2020-8492

  • python2.7 Ubuntu 16.04 LTS 2.7.12-1ubuntu0~16.04.11
  • python2.7 Ubuntu 18.04 LTS 2.7.17-1~18.04ubuntu1
  • python2.7 Ubuntu 20.04 LTS 2.7.18-1~20.04.1
  • python3.5 Ubuntu 16.04 LTS 3.5.2-2ubuntu0~16.04.10
  • python3.6 Ubuntu 18.04 LTS 3.6.9-1~18.04ubuntu1
  • python3.7 Ubuntu 18.04 LTS 3.7.5-2ubuntu1~18.04.2
  • python3.8 Ubuntu 18.04 LTS 3.8.0-3ubuntu1~18.04.2
  • python3.8 Ubuntu 20.04 LTS 3.8.2-1ubuntu1.1

ubuntu advisories UBUNTU-CVE-2020-8492

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

  • pytz RHEL 8 2019.3-3.module+el8.2.0+5234+f98739b6
  • babel RHEL 8 2.7.0-10.module+el8.2.0+5234+f98739b6
  • numpy RHEL 8 1.17.3-5.module+el8.3.0+7187+a27ec44b
  • scipy RHEL 8 1.3.1-4.module+el8.2.0+5234+f98739b6
  • Cython RHEL 8 0.29.14-4.module+el8.2.0+5234+f98739b6
  • PyYAML RHEL 8 5.3.1-1.module+el8.3.0+7187+a27ec44b
  • mod_wsgi RHEL 8 4.6.8-3.module+el8.2.0+5234+f98739b6
  • python38 RHEL 8 3.8.3-3.module+el8.3.0+7680+79e7e61a

red hat advisories RHSA-2020:4641RHSA-2020:4285RHSA-2020:3888RHSA-2020:4433

  • python3 SLE Module for Basesystem 15 SP4, SLE Module for Basesystem 15 SP3, SLE Micro 5.3 +5 more 3.6.15-150300.10.37.2
  • python3-core SLE Module for Development Tools 15 SP4, SLE Module for Development Tools 15 SP3, SLE Module for Basesystem 15 SP4 +7 more 3.6.15-150300.10.37.2
  • python3-documentation openSUSE Leap 15.4, openSUSE Leap 15.3 3.6.15-150300.10.37.1
  • python3 SLES for SAP 15, SLES 15-LTSS, SLE Module for Basesystem 15 SP2 +3 more 3.6.12-3.67.2
  • python3-core SLES for SAP 15, SLES 15-LTSS, SLE Module for Development Tools 15 SP2 +5 more 3.6.12-3.67.2
  • python36 SLES for SAP 12 SP5, SLES 12 SP5 3.6.12-4.25.1
  • python36-core SLES for SAP 12 SP5, SLES 12 SP5 3.6.12-4.25.1
  • python36 SLES for SAP 12 SP5, SLES 12 SP5 3.6.12-4.22.2

suse advisories SUSE-SU-2022:4281-1SUSE-SU-2020:3930-1SUSE-SU-2020:3865-1SUSE-SU-2020:3563-1SUSE-SU-2020:1524-1SUSE-SU-2020:0854-1

  • python315 openSUSE Tumbleweed 3.15.0~a1-1.1
  • python314 openSUSE Tumbleweed 3.14.0~a1-1.1
  • python313 openSUSE Tumbleweed 3.13.0~b3-1.1
  • python openSUSE Tumbleweed 2.7.18-8.1
  • python310 openSUSE Tumbleweed 3.10.0rc1-4.2
  • python36 openSUSE Tumbleweed 3.6.15-1.1
  • python38 openSUSE Tumbleweed 3.8.12-1.2
  • python39 openSUSE Tumbleweed 3.9.7-2.1

opensuse advisories openSUSE-SU-2025:15713-1openSUSE-SU-2024:14434-1openSUSE-SU-2024:14109-1openSUSE-SU-2024:11202-1openSUSE-SU-2024:11283-1openSUSE-SU-2024:11284-1

  • python38-cffi AlmaLinux 8 1.13.2-3.module_el8.6.0+2778+cd494b30
  • python38-idna AlmaLinux 8 2.8-6.module_el8.6.0+2778+cd494b30
  • python38-pytz AlmaLinux 8 2019.3-3.module_el8.6.0+2778+cd494b30
  • python38-scipy AlmaLinux 8 1.3.1-4.module_el8.6.0+2778+cd494b30
  • python38-Cython AlmaLinux 8 0.29.14-4.module_el8.6.0+2778+cd494b30
  • python38-chardet AlmaLinux 8 3.0.4-19.module_el8.6.0+2778+cd494b30
  • python38-pysocks AlmaLinux 8 1.7.1-4.module_el8.6.0+2778+cd494b30
  • python38-mod_wsgi AlmaLinux 8 4.6.8-3.module_el8.6.0+2778+cd494b30

almalinux advisories ALSA-2020:4641

  • pytz Rocky Linux 8 2019.3-3.module+el8.4.0+570+c2eaf144
  • babel Rocky Linux 8 2.7.0-10.module+el8.4.0+570+c2eaf144
  • numpy Rocky Linux 8 1.17.3-5.module+el8.4.0+570+c2eaf144
  • scipy Rocky Linux 8 1.3.1-4.module+el8.5.0+672+ab6eb015
  • scipy Rocky Linux 8 1.3.1-4.module+el8.4.0+570+c2eaf144
  • Cython Rocky Linux 8 0.29.14-4.module+el8.4.0+570+c2eaf144
  • PyYAML Rocky Linux 8 5.3.1-1.module+el8.4.0+570+c2eaf144
  • mod_wsgi Rocky Linux 8 4.6.8-3.module+el8.4.0+570+c2eaf144

rocky linux advisories RLSA-2020:4641

  • python3 Alpine 3.10 3.7.7-r0
  • python3 Alpine 3.24, Alpine 3.23, Alpine 3.22 +11 more 3.8.2-r0

alpine advisories ALPINE-CVE-2020-8492

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-2020-8492 updated cvss 6.5

python: wrong backtracking in urllib.request.AbstractBasicAuthHandler allows for a ReDoS

  • Red Hat Enterprise Linux 5 python Red Hat Enterprise Linux 6 python, tkinter, python-libs, python-test, python-tools
    affected: no fix planned “Out of support scope”
  • Red Hat Enterprise Linux 7 python, tkinter, python-libs, python-test, python-tools Red Hat Enterprise Linux 8 python2, python2-libs, python2-test, python2-tools, python2-tkinter Red Hat Software Collections python27-python, python27-tkinter, python27-python-libs, python27-python-test, python27-python-tools
    affected: no fix planned “Will not fix”
  • Red Hat Enterprise Linux AppStream (v. 8) python3-idle 3.6.8-31.el8, python3-test 3.6.8-31.el8, platform-python 3.6.8-31.el8, python3-tkinter 3.6.8-31.el8, pytz 2019.3-3.module+el8.2.0+5234+f98739b6, scipy 1.3.1-4.module+el8.2.0+5234+f98739b6, +63 more
    fixed: vendor fix RHSA-2020:4641
  • Red Hat Enterprise Linux BaseOS (v. 8) python3 3.6.8-31.el8, python3-libs 3.6.8-31.el8, python3-test 3.6.8-31.el8, platform-python 3.6.8-31.el8
    fixed: vendor fix RHSA-2020:4433
  • Red Hat Enterprise Linux Client (v. 7) python3 3.6.8-17.el7, python3-libs 3.6.8-17.el7 Red Hat Enterprise Linux Client Optional (v. 7) python3 3.6.8-17.el7, python3-idle 3.6.8-17.el7, python3-test 3.6.8-17.el7, python3-tkinter 3.6.8-17.el7 Red Hat Enterprise Linux ComputeNode (v. 7) python3 3.6.8-17.el7, python3-libs 3.6.8-17.el7 Red Hat Enterprise Linux ComputeNode Optional (v. 7) python3 3.6.8-17.el7, python3-idle 3.6.8-17.el7, python3-test 3.6.8-17.el7, python3-tkinter 3.6.8-17.el7 Red Hat Enterprise Linux Server (v. 7) python3 3.6.8-17.el7, python3-libs 3.6.8-17.el7 Red Hat Enterprise Linux Server Optional (v. 7) python3 3.6.8-17.el7, python3-idle 3.6.8-17.el7, python3-test 3.6.8-17.el7, python3-tkinter 3.6.8-17.el7
    +2 more products
    Red Hat Enterprise Linux Workstation (v. 7) python3 3.6.8-17.el7, python3-libs 3.6.8-17.el7 Red Hat Enterprise Linux Workstation Optional (v. 7) python3 3.6.8-17.el7, python3-idle 3.6.8-17.el7, python3-test 3.6.8-17.el7, python3-tkinter 3.6.8-17.el7
    fixed: vendor fix RHSA-2020:3888
  • Red Hat Software Collections for Red Hat Enterprise Linux Server (v. 6) rh-python36-python 3.6.12-1.el6, rh-python36-python-pip 9.0.1-5.el6, rh-python36-python-libs 3.6.12-1.el6, rh-python36-python-test 3.6.12-1.el6, rh-python36-python-tools 3.6.12-1.el6, rh-python36-python-tkinter 3.6.12-1.el6, +1 more Red Hat Software Collections for Red Hat Enterprise Linux Server (v. 7) rh-python36-python 3.6.12-1.el7, rh-python36-python-pip 9.0.1-5.el7, rh-python36-python-libs 3.6.12-1.el7, rh-python36-python-test 3.6.12-1.el7, rh-python36-python-tools 3.6.12-1.el7, rh-python36-python-tkinter 3.6.12-1.el7, +1 more Red Hat Software Collections for Red Hat Enterprise Linux Server EUS (v. 7.6) rh-python36-python 3.6.12-1.el7, rh-python36-python-pip 9.0.1-5.el7, rh-python36-python-libs 3.6.12-1.el7, rh-python36-python-test 3.6.12-1.el7, rh-python36-python-tools 3.6.12-1.el7, rh-python36-python-tkinter 3.6.12-1.el7, +1 more Red Hat Software Collections for Red Hat Enterprise Linux Server EUS (v. 7.7) rh-python36-python 3.6.12-1.el7, rh-python36-python-pip 9.0.1-5.el7, rh-python36-python-libs 3.6.12-1.el7, rh-python36-python-test 3.6.12-1.el7, rh-python36-python-tools 3.6.12-1.el7, rh-python36-python-tkinter 3.6.12-1.el7, +1 more Red Hat Software Collections for Red Hat Enterprise Linux Workstation (v. 6) rh-python36-python 3.6.12-1.el6, rh-python36-python-pip 9.0.1-5.el6, rh-python36-python-libs 3.6.12-1.el6, rh-python36-python-test 3.6.12-1.el6, rh-python36-python-tools 3.6.12-1.el6, rh-python36-python-tkinter 3.6.12-1.el6, +1 more Red Hat Software Collections for Red Hat Enterprise Linux Workstation (v. 7) rh-python36-python 3.6.12-1.el7, rh-python36-python-pip 9.0.1-5.el7, rh-python36-python-libs 3.6.12-1.el7, rh-python36-python-test 3.6.12-1.el7, rh-python36-python-tools 3.6.12-1.el7, rh-python36-python-tkinter 3.6.12-1.el7, +1 more
    fixed: vendor fix RHSA-2020:4285
  • Red Hat Enterprise Linux 8 scipy, python36, python-nose, python-wheel, python3-bson, python3-nose, +19 more Red Hat Software Collections rh-python38-python, rh-python38-python-idle, rh-python38-python-libs, rh-python38-python-test, rh-python38-python-tkinter, rh-python38-python-rpm-macros, +1 more
    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

cisa ICSA-23-348-10 updated cvss 6.5

Siemens SIMATIC S7-1500

  • Siemens SIMATIC S7-1500 CPU 1518-4 PN/DP MFP (6ES7518-4AX00-1AB0) >= 3.1.0, < 3.1.5 Siemens SIMATIC S7-1500 CPU 1518-4 PN/DP MFP (6ES7518-4AX00-1AC0) >= 3.1.0, < 3.1.5 Siemens SIMATIC S7-1500 CPU 1518F-4 PN/DP MFP (6ES7518-4FX00-1AB0) >= 3.1.0, < 3.1.5 Siemens SIMATIC S7-1500 CPU 1518F-4 PN/DP MFP (6ES7518-4FX00-1AC0) >= 3.1.0, < 3.1.5 Siemens SIPLUS S7-1500 CPU 1518-4 PN/DP MFP (6AG1518-4AX00-4AC0) >= 3.1.0, < 3.1.5
    affected: fixed in V3.1.5, mitigation support.industry.siemens.com

Facts from CISA's republication of the vendor's own advisory (CSAF); the linked advisory is the authoritative source. CISA notification · csaf

CISA SSVC

Exploitation
none
Automatable
no
Technical impact
partial
Assessed
32 d ago

Exploit prediction

6.62% chance of exploitation in the next 30 days, higher than 93% of all scored CVEs (FIRST EPSS, 2026-11-08).

Exploits and checks

  • python-security.readthedocs.io https://python-security.readthedocs.io/vuln/urllib-basic-auth-regex.html referenced PoC, tagged "exploit" by a source, unverified

CVSS scores

assigned by version score vector
CISA ADP 3.1 6.5 CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H
NVD 3.1 6.5 CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H
CNA 3.1 6.5 CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H
NVD 2.0 7.1 AV:N/AC:M/Au:N/C:N/I:N/A:C
OSV 3.1 6.5 CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H

Affected packages

ecosystem package affected fixed in
bitnami libpython
>=2.7.0, <2.7.18
>=3.5.0, <3.5.10
>=3.6.0, <3.6.11
>=3.7.0, <3.7.7
>=3.8.0, <3.8.2
2.7.18
3.5.10
3.6.11
3.7.7
3.8.2
bitnami python
>=2.7.0, <2.7.18
>=3.5.0, <3.5.10
>=3.6.0, <3.6.11
>=3.7.0, <3.7.7
>=3.8.0, <3.8.2
2.7.18
3.5.10
3.6.11
3.7.7
3.8.2
bitnami python-min
>=2.7.0, <2.7.18
>=3.5.0, <3.5.10
>=3.6.0, <3.6.11
>=3.7.0, <3.7.7
>=3.8.0, <3.8.2
2.7.18
3.5.10
3.6.11
3.7.7
3.8.2

Affected products

  • Siemens SIMATIC S7-1500 CPU 1518-4 PN/DP MFP
  • Siemens SIMATIC S7-1500 CPU 1518F-4 PN/DP MFP
  • Siemens SIPLUS S7-1500 CPU 1518-4 PN/DP MFP

Classification

Weakness
  • CWE-400 Uncontrolled Resource Consumption

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.