high
7.5
CWE
400 835
Advisory Published
Advisory Published
CVE Published
Updated

CVE-2021-33503

First published: Tue Jun 01 2021(Updated: )

### Impact When provided with a URL containing many `@` characters in the authority component the authority regular expression exhibits catastrophic backtracking causing a denial of service if a URL were passed as a parameter or redirected to via an HTTP redirect. ### Patches The issue has been fixed in urllib3 v1.26.5. ### References - [CVE-2021-33503](https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2021-33503) - [JVNVU#92413403 (English)](https://jvn.jp/en/vu/JVNVU92413403/) - [JVNVU#92413403 (Japanese)](https://jvn.jp/vu/JVNVU92413403/) - [urllib3 v1.26.5](https://github.com/urllib3/urllib3/releases/tag/1.26.5) ### For more information If you have any questions or comments about this advisory: * Ask in our [community Discord](https://discord.gg/urllib3) * Email [sethmichaellarson@gmail.com](mailto:sethmichaellarson@gmail.com)

Credit: cve@mitre.org cve@mitre.org cve@mitre.org

Affected SoftwareAffected VersionHow to fix
redhat/automation-hub<0:4.2.6-1.el7
0:4.2.6-1.el7
redhat/python3-chardet<0:3.0.4-3.el7
0:3.0.4-3.el7
redhat/python3-click<0:7.1.2-3.el7
0:7.1.2-3.el7
redhat/python3-gnupg<0:0.4.6-3.el7
0:0.4.6-3.el7
redhat/python3-jinja2<0:2.11.2-3.el7
0:2.11.2-3.el7
redhat/python3-markupsafe<0:1.1.1-4.el7
0:1.1.1-4.el7
redhat/python3-semantic-version<0:2.8.5-3.el7
0:2.8.5-3.el7
redhat/python-galaxy-ng<0:4.2.6-1.el7
0:4.2.6-1.el7
redhat/python-requests<0:2.25.1-1.el7
0:2.25.1-1.el7
redhat/python-urllib3<0:1.26.5-1.el7
0:1.26.5-1.el7
redhat/automation-hub<0:4.2.6-1.el8
0:4.2.6-1.el8
redhat/python3-click<0:7.1.2-3.el8
0:7.1.2-3.el8
redhat/python3-gnupg<0:0.4.6-3.el8
0:0.4.6-3.el8
redhat/python3-jinja2<0:2.11.2-3.el8
0:2.11.2-3.el8
redhat/python3-markupsafe<0:1.1.1-4.el8
0:1.1.1-4.el8
redhat/python3-semantic-version<0:2.8.5-3.el8
0:2.8.5-3.el8
redhat/python-galaxy-ng<0:4.2.6-1.el8
0:4.2.6-1.el8
redhat/python-requests<0:2.25.1-1.el8
0:2.25.1-1.el8
redhat/python-urllib3<0:1.26.5-1.el8
0:1.26.5-1.el8
redhat/rh-python38-babel<0:2.7.0-12.el7
0:2.7.0-12.el7
redhat/rh-python38-python<0:3.8.11-2.el7
0:3.8.11-2.el7
redhat/rh-python38-python-cryptography<0:2.8-5.el7
0:2.8-5.el7
redhat/rh-python38-python-jinja2<0:2.10.3-6.el7
0:2.10.3-6.el7
redhat/rh-python38-python-lxml<0:4.4.1-7.el7
0:4.4.1-7.el7
redhat/rh-python38-python-pip<0:19.3.1-2.el7
0:19.3.1-2.el7
redhat/rh-python38-python-urllib3<0:1.25.7-7.el7
0:1.25.7-7.el7
pip/urllib3>=1.25.4<1.26.5
1.26.5
redhat/urllib3<1.26.5
1.26.5
Python urllib3>=1.25.4<1.26.5
Fedoraproject Fedora=33
Fedoraproject Fedora=34
Oracle Enterprise Manager Ops Center=12.4.0.0
Oracle Instantis Enterprisetrack=17.1
Oracle Instantis Enterprisetrack=17.2
Oracle Instantis Enterprisetrack=17.3
Oracle ZFS Storage Appliance Kit=8.8
>=1.25.4<1.26.5
=33
=34
=12.4.0.0
=17.1
=17.2
=17.3
=8.8

Remedy

https://github.com/urllib3/urllib3/commit/2d4a3fee6de2fa45eb82169361918f759269b4ec

Remedy

https://www.oracle.com/security-alerts/cpuoct2021.html

Remedy

Mitigation for this issue is either not available or the currently available options do not meet the Red Hat Product Security criteria comprising ease of use and deployment, applicability to widespread installation base or stability.

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Reference Links

Parent vulnerabilities

(Appears in the following advisories)

Frequently Asked Questions

  • What is CVE-2021-33503?

    CVE-2021-33503 is a vulnerability in urllib3 before version 1.26.5 that allows for denial of service attacks through a regex backtracking issue.

  • What is the impact of CVE-2021-33503?

    CVE-2021-33503 can cause a denial of service if a URL with many '@' characters in the authority component is passed as a parameter or redirected to via an HTTP redirect.

  • How severe is CVE-2021-33503?

    CVE-2021-33503 has a severity rating of 7.5 (High).

  • How do I fix CVE-2021-33503?

    To fix CVE-2021-33503, update urllib3 to version 1.26.5 or apply the patches provided by the respective vendors.

  • Where can I find more information about CVE-2021-33503?

    You can find more information about CVE-2021-33503 at the following references: [GitHub Advisory](https://github.com/advisories/GHSA-q2q7-5pp4-w6pg), [urllib3 Commit](https://github.com/urllib3/urllib3/commit/2d4a3fee6de2fa45eb82169361918f759269b4ec), [Fedora Security Announcement](https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/6SCV7ZNAHS3E6PBFLJGENCDRDRWRZZ6W/)

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