UBUNTU-CVE-2021-21708

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    UBUNTU-CVE-2021-21708

    Published: 31 Dec 2021Last Modified: 22 Apr 2026
    Upstream:
    CVE-2021-21708
    Aliases:
    USN-5303-1

    Summary:

    Details: In PHP versions 7.4.x below 7.4.28, 8.0.x below 8.0.16, and 8.1.x below 8.1.3, when using filter functions with FILTER_VALIDATE_FLOAT filter and min/max limits, if the filter fails, there is a possibility to trigger use of allocated memory after free, which can result it crashes, and potentially in overwrite of other memory chunks and RCE. This issue affects: code that uses FILTER_VALIDATE_FLOAT with min/max limits.

    References: https://ubuntu.com/security/CVE-2021-21708, https://nakedsecurity.sophos.com/2022/02/18/irony-alert-php-fixes-security-flaw-in-input-validation-code/, https://www.php.net/ChangeLog-8.php#PHP_8_1, https://www.php.net/ChangeLog-7.php#PHP_7_4, https://ubuntu.com/security/notices/USN-5303-1, https://www.cve.org/CVERecord?id=CVE-2021-21708

    Affected packages

    Package

    Name: php7.4

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

    Affected ranges

    Type: ECOSYSTEM

    Events:

    Introduced- 0
    Fixed -7.4.3-4ubuntu2.9

    Affected versions

    7.4.3-4build1
    7.4.3-4build2
    7.4.3-4ubuntu1
    7.4.3-4ubuntu1.1
    7.4.3-4ubuntu2.2
    7.4.3-4ubuntu2.4
    7.4.3-4ubuntu2.5
    7.4.3-4ubuntu2.6
    7.4.3-4ubuntu2.7
    7.4.3-4ubuntu2.8

    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-2021-21708 | CVE-DB