CVE-2021-33503
An issue was discovered in urllib3 before 1.26.5. When provided with a URL containing many @ characters in the authority component, the authority regular expression exhibits catastrophic backtracking,
02 Description
An issue was discovered in urllib3 before 1.26.5. When provided with a URL containing many @ characters in the authority component, the authority regular expression exhibits catastrophic backtracking,
03 Exploitation and scoring
- Exploitation
- Not assessed. CISA has not published an exploitation assessment for this record, and it is not in the KEV catalog. That is an absence of assessment, not a finding of no risk.
- SSVC decision
- Not assessed by CISA
- EPSS probability
- 3.27% probability of exploitation activity in the next 30 days.
- EPSS percentile
- Equal to or higher than the score of 88.3% of scored records. A rank, not a probability.
- NVD base score
- 7.5 (CVSS v3.x), scored by the NVD independently of the CNA.
- NVD CVSS vector
- CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
- NVD analysis status
- Modified. NVD last modified this record on 2026-06-17.
- Red Hat severity
- Moderate. Red Hat's rating for its own products, not a CVSS rating.
Exploit-prediction scores from FIRST. Independent scoring and analysis status from the NVD. Vendor severity from Red Hat. Exploitation assessment and catalog membership from CISA.
04 Metadata
- Published
- 2021-06-29 10:55Z5 YR AGO
- Last updated
- 2024-08-03 23:50Z2 YR AGO
- Reserved
- 2021-05-21
- Assigning CNA
- mitre
- Record state
- PUBLISHED
- Severity
- Not rated by the issuing CNA
- CNA CVSS vector
- Not published by the issuing CNA
- Weaknesses
- Data version
- 5.1
- Document digest
- 3d0230102976e27a9b30103973bb0ed59c858ee60ad14d88564998051fd49f56
05 Affected products
06 References
- lists.fedoraproject.orgFEDORA-2021-a6bde7ab18https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/FMUGWEAUYGGHTPPXT6YBD53WYXQGVV73/
- lists.fedoraproject.orgFEDORA-2021-9c5f3b8aaehttps://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/6SCV7ZNAHS3E6PBFLJGENCDRDRWRZZ6W/
- security.gentoo.orgGLSA-202107-36https://security.gentoo.org/glsa/202107-36
- www.oracle.comhttps://www.oracle.com/security-alerts/cpuoct2021.html
- github.comhttps://github.com/advisories/GHSA-q2q7-5pp4-w6pg
- github.comhttps://github.com/urllib3/urllib3/commit/2d4a3fee6de2fa45eb82169361918f759269b4ec
07 Fixed in
AlmaLinux 8
- python38-Cython Fixed in 0.29.14-4.module_el8.6.0+2778+cd494b30
- python38-PyMySQL Fixed in 0.10.1-1.module_el8.6.0+2778+cd494b30
- python38-asn1crypto Fixed in 1.2.0-3.module_el8.6.0+2778+cd494b30
- python38-atomicwrites Fixed in 1.3.0-8.module_el8.6.0+2778+cd494b30
- python38-attrs Fixed in 19.3.0-3.module_el8.6.0+2778+cd494b30
- python38-babel Fixed in 2.7.0-11.module_el8.6.0+2778+cd494b30
- python38-cffi Fixed in 1.13.2-3.module_el8.6.0+2778+cd494b30
- python38-chardet Fixed in 3.0.4-19.module_el8.6.0+2778+cd494b30
- python38-cryptography Fixed in 2.8-3.module_el8.6.0+2778+cd494b30
- python38-idna Fixed in 2.8-6.module_el8.6.0+2778+cd494b30
- python38-jinja2 Fixed in 2.10.3-5.module_el8.6.0+2778+cd494b30
- python38-markupsafe Fixed in 1.1.1-6.module_el8.6.0+2778+cd494b30
- python38-mod_wsgi Fixed in 4.6.8-3.module_el8.6.0+2778+cd494b30
- python38-more-itertools Fixed in 7.2.0-5.module_el8.6.0+2778+cd494b30
- python38-numpy Fixed in 1.17.3-6.module_el8.6.0+2778+cd494b30
- python38-numpy-doc Fixed in 1.17.3-6.module_el8.6.0+2778+cd494b30
- python38-numpy-f2py Fixed in 1.17.3-6.module_el8.6.0+2778+cd494b30
- python38-packaging Fixed in 19.2-3.module_el8.6.0+2778+cd494b30
- python38-pluggy Fixed in 0.13.0-3.module_el8.6.0+2778+cd494b30
- python38-ply Fixed in 3.11-10.module_el8.6.0+2778+cd494b30
- python38-psutil Fixed in 5.6.4-4.module_el8.6.0+2778+cd494b30
- python38-psycopg2 Fixed in 2.8.4-4.module_el8.6.0+2778+cd494b30
- python38-psycopg2-doc Fixed in 2.8.4-4.module_el8.6.0+2778+cd494b30
- python38-psycopg2-tests Fixed in 2.8.4-4.module_el8.6.0+2778+cd494b30
- python38-py Fixed in 1.8.0-8.module_el8.6.0+2778+cd494b30
- python38-pycparser Fixed in 2.19-3.module_el8.6.0+2778+cd494b30
- python38-pyparsing Fixed in 2.4.5-3.module_el8.6.0+2778+cd494b30
- python38-pysocks Fixed in 1.7.1-4.module_el8.6.0+2778+cd494b30
- python38-pytest Fixed in 4.6.6-3.module_el8.6.0+2778+cd494b30
- python38-pytz Fixed in 2019.3-3.module_el8.6.0+2778+cd494b30
- python38-pyyaml Fixed in 5.4.1-1.module_el8.6.0+2778+cd494b30
- python38-requests Fixed in 2.22.0-9.module_el8.6.0+2778+cd494b30
- python38-scipy Fixed in 1.3.1-4.module_el8.6.0+2778+cd494b30
- python38-setuptools Fixed in 41.6.0-5.module_el8.6.0+2778+cd494b30
- python38-setuptools-wheel Fixed in 41.6.0-5.module_el8.6.0+2778+cd494b30
- python38-six Fixed in 1.12.0-10.module_el8.6.0+2778+cd494b30
- python38-urllib3 Fixed in 1.25.7-5.module_el8.6.0+2778+cd494b30
- python38-wcwidth Fixed in 0.1.7-16.module_el8.6.0+2778+cd494b30
- python38-wheel Fixed in 0.33.6-6.module_el8.6.0+2778+cd494b30
- python38-wheel-wheel Fixed in 0.33.6-6.module_el8.6.0+2778+cd494b30
36 further packages in AlmaLinux 8 not shown (first 40 listed).
Source: AlmaLinux, AlmaLinux OS. Copyright (c) 2023 AlmaLinux OS. Licensed under MIT License. Received through OSV.dev. Reformatted by exploit.cc.
Arch Linux
- python-urllib3 Fixed in 1.26.5-1
Source: Arch Linux Security Tracker, the Arch Linux security team. Reformatted by exploit.cc.
CloudLinux 8
- python38-Cython Fixed in 0.29.14-4.module_el8.6.0+2778+cd494b30
- python38-PyMySQL Fixed in 0.10.1-1.module_el8.6.0+2778+cd494b30
- python38-asn1crypto Fixed in 1.2.0-3.module_el8.6.0+2778+cd494b30
- python38-atomicwrites Fixed in 1.3.0-8.module_el8.6.0+2778+cd494b30
- python38-attrs Fixed in 19.3.0-3.module_el8.6.0+2778+cd494b30
- python38-babel Fixed in 2.7.0-11.module_el8.6.0+2778+cd494b30
- python38-cffi Fixed in 1.13.2-3.module_el8.6.0+2778+cd494b30
- python38-chardet Fixed in 3.0.4-19.module_el8.6.0+2778+cd494b30
- python38-cryptography Fixed in 2.8-3.module_el8.6.0+2778+cd494b30
- python38-idna Fixed in 2.8-6.module_el8.6.0+2778+cd494b30
- python38-jinja2 Fixed in 2.10.3-5.module_el8.6.0+2778+cd494b30
- python38-markupsafe Fixed in 1.1.1-6.module_el8.6.0+2778+cd494b30
- python38-mod_wsgi Fixed in 4.6.8-3.module_el8.6.0+2778+cd494b30
- python38-more-itertools Fixed in 7.2.0-5.module_el8.6.0+2778+cd494b30
- python38-numpy Fixed in 1.17.3-6.module_el8.6.0+2778+cd494b30
- python38-numpy-doc Fixed in 1.17.3-6.module_el8.6.0+2778+cd494b30
- python38-numpy-f2py Fixed in 1.17.3-6.module_el8.6.0+2778+cd494b30
- python38-packaging Fixed in 19.2-3.module_el8.6.0+2778+cd494b30
- python38-pluggy Fixed in 0.13.0-3.module_el8.6.0+2778+cd494b30
- python38-ply Fixed in 3.11-10.module_el8.6.0+2778+cd494b30
- python38-psutil Fixed in 5.6.4-4.module_el8.6.0+2778+cd494b30
- python38-psycopg2 Fixed in 2.8.4-4.module_el8.6.0+2778+cd494b30
- python38-psycopg2-doc Fixed in 2.8.4-4.module_el8.6.0+2778+cd494b30
- python38-psycopg2-tests Fixed in 2.8.4-4.module_el8.6.0+2778+cd494b30
- python38-py Fixed in 1.8.0-8.module_el8.6.0+2778+cd494b30
- python38-pycparser Fixed in 2.19-3.module_el8.6.0+2778+cd494b30
- python38-pyparsing Fixed in 2.4.5-3.module_el8.6.0+2778+cd494b30
- python38-pysocks Fixed in 1.7.1-4.module_el8.6.0+2778+cd494b30
- python38-pytest Fixed in 4.6.6-3.module_el8.6.0+2778+cd494b30
- python38-pytz Fixed in 2019.3-3.module_el8.6.0+2778+cd494b30
- python38-pyyaml Fixed in 5.4.1-1.module_el8.6.0+2778+cd494b30
- python38-requests Fixed in 2.22.0-9.module_el8.6.0+2778+cd494b30
- python38-scipy Fixed in 1.3.1-4.module_el8.6.0+2778+cd494b30
- python38-setuptools Fixed in 41.6.0-5.module_el8.6.0+2778+cd494b30
- python38-setuptools-wheel Fixed in 41.6.0-5.module_el8.6.0+2778+cd494b30
- python38-six Fixed in 1.12.0-10.module_el8.6.0+2778+cd494b30
- python38-urllib3 Fixed in 1.25.7-5.module_el8.6.0+2778+cd494b30
- python38-wcwidth Fixed in 0.1.7-16.module_el8.6.0+2778+cd494b30
- python38-wheel Fixed in 0.33.6-6.module_el8.6.0+2778+cd494b30
- python38-wheel-wheel Fixed in 0.33.6-6.module_el8.6.0+2778+cd494b30
36 further packages in CloudLinux 8 not shown (first 40 listed).
Derived from AlmaLinux 8. Partial coverage: only packages taken from AlmaLinux 8 are listed.
Source: CloudLinux errata, CloudLinux Inc. Derived from: AlmaLinux, AlmaLinux OS. Copyright (c) 2023 AlmaLinux OS. Licensed under MIT License. Received through OSV.dev. Reformatted by exploit.cc.
Debian 12
- python-urllib3 Fixed in 1.26.5-1~exp1
Source: Debian Security Tracker, the Debian security team. Received through OSV.dev. Reformatted by exploit.cc.
Debian 13
- python-urllib3 Fixed in 1.26.5-1~exp1
Source: Debian Security Tracker, the Debian security team. Received through OSV.dev. Reformatted by exploit.cc.
Debian 14
- python-urllib3 Fixed in 1.26.5-1~exp1
Source: Debian Security Tracker, the Debian security team. Received through OSV.dev. Reformatted by exploit.cc.
Ubuntu 20.04 LTS
- python-pip Fixed in 20.0.2-5ubuntu1.7
- python-urllib3 Fixed in 1.25.8-2ubuntu0.2
Source: Ubuntu, Canonical Ltd. Licensed under CC BY-SA 4.0. Received through OSV.dev. Reformatted by exploit.cc.
A release or ecosystem missing from this list has no record here. It may be unaffected or not covered by the source. Source notices and licences.