UBUNTU-CVE-2021-38503

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    UBUNTU-CVE-2021-38503

    Published: 3 Nov 2021Last Modified: 22 Apr 2026
    Upstream:
    CVE-2021-38503

    Summary:

    Details: The iframe sandbox rules were not correctly applied to XSLT stylesheets, allowing an iframe to bypass restrictions such as executing scripts or navigating the top-level frame. This vulnerability affects Firefox < 94, Thunderbird < 91.3, and Firefox ESR < 91.3.

    References: https://ubuntu.com/security/CVE-2021-38503, https://www.mozilla.org/en-US/security/advisories/mfsa2021-48/#CVE-2021-38503, https://www.mozilla.org/en-US/security/advisories/mfsa2021-49/#CVE-2021-38503, https://ubuntu.com/security/notices/USN-5131-1, https://ubuntu.com/security/notices/USN-5152-1, https://ubuntu.com/security/notices/USN-5248-1, https://www.cve.org/CVERecord?id=CVE-2021-38503

    Affected packages

    Package

    Name: firefox

    Purl: pkg:deb/ubuntu/[email protected]+build3-0ubuntu0.18.04.1?arch=source&distro=bionic

    Affected ranges

    Type: ECOSYSTEM

    Events:

    Introduced- 0
    Fixed -94.0+build3-0ubuntu0.18.04.1

    Affected versions

    56.0+build6-0ubuntu1

    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-2021-38503 | CVE-DB