CVE-2021-42717

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    CVE-2021-42717

    Published: 7 Dec 2021Last Modified: 27 Aug 2026

    Summary:

    Details: ModSecurity 3.x through 3.0.5 mishandles excessively nested JSON objects. Crafted JSON objects with nesting tens-of-thousands deep could result in the web server being unable to service legitimate requests. Even a moderately large (e.g., 300KB) HTTP request can occupy one of the limited NGINX worker processes for minutes and consume almost all of the available CPU on the machine. Modsecurity 2 is similarly vulnerable: the affected versions include 2.8.0 through 2.9.4.

    References: https://lists.debian.org/debian-lts-announce/2022/05/msg00042.html, https://www.debian.org/security/2021/dsa-5023, https://www.oracle.com/security-alerts/cpuapr2022.html, https://www.trustwave.com/en-us/resources/blogs/spiderlabs-blog/modsecurity-dos-vulnerability-in-json-parsing-cve-2021-42717/

    Affected packages

    Package

    Name:

    Purl:

    Affected ranges

    Type: GIT

    Events:

    Introduced- c1cd668acb820824e791ba802396c60900eae9c1
    Fixed -c3d7f4b560797a052681dcffb97a22bb906487cd

    Affected versions

    v3.0.5
    v3.0.4
    v3.0.3
    v3.0.2
    v3.0.1
    v3.0.0

    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
    CVE-2021-42717 | CVE-DB