UBUNTU-CVE-2021-33503

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    UBUNTU-CVE-2021-33503

    Published: 29 Jun 2021Last Modified: 4 Feb 2026
    Upstream:
    CVE-2021-33503
    Aliases:
    USN-5812-1

    Summary:

    Details: 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, causing a denial of service if a URL were passed as a parameter or redirected to via an HTTP redirect.

    References: https://ubuntu.com/security/CVE-2021-33503, https://github.com/advisories/GHSA-q2q7-5pp4-w6pg, https://github.com/urllib3/urllib3/commit/2d4a3fee6de2fa45eb82169361918f759269b4ec, https://ubuntu.com/security/notices/USN-5812-1, https://www.cve.org/CVERecord?id=CVE-2021-33503

    Affected packages

    Package

    Name: python-pip

    Purl: pkg:deb/ubuntu/[email protected]?arch=source&distro=focal

    Affected ranges

    Type: ECOSYSTEM

    Events:

    Introduced- 0
    Fixed -20.0.2-5ubuntu1.7

    Affected versions

    18.1-5

    Common Vulnerability Scoring System

    Attack Vector
    Network
    Adjacent
    Local
    Physical
    Privileges Required
    None
    Low
    High
    User Interaction
    None
    Required
    Scope
    Unchanged
    Changed
    Confidentiality
    None
    Low
    High
    Integrity
    None
    Low
    High
    Availability
    None
    Low
    High
    UBUNTU-CVE-2021-33503 | CVE-DB