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    CVE-2023-4921

    A use-after-free vulnerability in the Linux kernel's net/sched: sch_qfq component can be exploited to achieve local privilege escalation. When the plug qdisc is used as a class of the qfq qdisc, sending network packets triggers use-after-free in qfq_dequeue() due to the incorrect .peek handler of sch_plug and lack of error checking in agg_dequeue(). We recommend upgrading past commit 8fc134fee27f2263988ae38920bc03da416b03d8.

    Published:Sep 5, 2023
    Last Modified:Feb 25, 2026
    EPS:Sep 12, 2023
    EPSS Score:0.00014
    CVSS Score:7.8

    Affected Products

    Vendor
    Debian
    Product
    Debian Linux
    Vendor
    Linux
    Product
    Linux Kernel
    Vendor
    Redhat
    Product
    Enterprise Linux
    Vendor
    Redhat
    Product
    Rhel Aus
    Vendor
    Redhat
    Product
    Rhel E4s
    Vendor
    Redhat
    Product
    Rhel Els
    Vendor
    Redhat
    Product
    Rhel Eus
    Vendor
    Redhat
    Product
    Rhel Extras Rt
    Vendor
    Redhat
    Product
    Rhel Tus
    Vendor
    Redhat
    Product
    Rhev Hypervisor

    Exploits

    https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=8fc134fee27f2263988ae38920bc03da416b03d8https://kernel.dance/8fc134fee27f2263988ae38920bc03da416b03d8https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=8fc134fee27f2263988ae38920bc03da416b03d8https://kernel.dance/8fc134fee27f2263988ae38920bc03da416b03d8

    Common Weakness Enumeration

    CWE-416 Use After Free

    Common Attack Pattern Enumeration and Classification (CAPEC)

    No CAPEC recorded yet

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    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