{
  "threat_severity" : "Moderate",
  "public_date" : "2021-10-13T12:00:00Z",
  "bugzilla" : {
    "description" : "kernel: eBPF verification flaw",
    "id" : "2000457",
    "url" : "https://bugzilla.redhat.com/show_bug.cgi?id=2000457"
  },
  "cvss3" : {
    "cvss3_base_score" : "6.7",
    "cvss3_scoring_vector" : "CVSS:3.1/AV:L/AC:L/PR:H/UI:N/S:U/C:H/I:H/A:H",
    "status" : "verified"
  },
  "cwe" : "CWE-697",
  "details" : [ "This vulnerability allows local attackers to escalate privileges on affected installations of Linux Kernel 5.14-rc3. An attacker must first obtain the ability to execute low-privileged code on the target system in order to exploit this vulnerability. The specific flaw exists within the handling of eBPF programs. The issue results from the lack of proper validation of user-supplied eBPF programs, which can result in a type confusion condition. An attacker can leverage this vulnerability to escalate privileges and execute arbitrary code in the context of the kernel. Was ZDI-CAN-14689.", "A vulnerability was found in Linux Kernel, where a type confusion problem in check_map_func_compatibility() may lead to free arbitrary kernel memory." ],
  "acknowledgement" : "Red Hat would like to thank Ryota Shiga (Flatt Security) for reporting this issue.",
  "affected_release" : [ {
    "product_name" : "Red Hat Enterprise Linux 8.6 Extended Update Support",
    "release_date" : "2024-02-07T00:00:00Z",
    "advisory" : "RHSA-2024:0724",
    "cpe" : "cpe:/o:redhat:rhel_eus:8.6",
    "package" : "kernel-0:4.18.0-372.91.1.el8_6"
  }, {
    "product_name" : "Red Hat Virtualization 4 for Red Hat Enterprise Linux 8",
    "release_date" : "2024-02-07T00:00:00Z",
    "advisory" : "RHSA-2024:0724",
    "cpe" : "cpe:/o:redhat:rhev_hypervisor:4.4::el8",
    "package" : "kernel-0:4.18.0-372.91.1.el8_6"
  } ],
  "package_state" : [ {
    "product_name" : "Red Hat Enterprise Linux 5",
    "fix_state" : "Not affected",
    "package_name" : "kernel",
    "cpe" : "cpe:/o:redhat:enterprise_linux:5"
  }, {
    "product_name" : "Red Hat Enterprise Linux 6",
    "fix_state" : "Not affected",
    "package_name" : "kernel",
    "cpe" : "cpe:/o:redhat:enterprise_linux:6"
  }, {
    "product_name" : "Red Hat Enterprise Linux 7",
    "fix_state" : "Out of support scope",
    "package_name" : "kernel",
    "cpe" : "cpe:/o:redhat:enterprise_linux:7"
  }, {
    "product_name" : "Red Hat Enterprise Linux 7",
    "fix_state" : "Out of support scope",
    "package_name" : "kernel-rt",
    "cpe" : "cpe:/o:redhat:enterprise_linux:7"
  }, {
    "product_name" : "Red Hat Enterprise Linux 8",
    "fix_state" : "Affected",
    "package_name" : "kernel",
    "cpe" : "cpe:/o:redhat:enterprise_linux:8"
  }, {
    "product_name" : "Red Hat Enterprise Linux 8",
    "fix_state" : "Affected",
    "package_name" : "kernel-rt",
    "cpe" : "cpe:/o:redhat:enterprise_linux:8"
  }, {
    "product_name" : "Red Hat Enterprise Linux 9",
    "fix_state" : "Will not fix",
    "package_name" : "kernel",
    "cpe" : "cpe:/o:redhat:enterprise_linux:9"
  } ],
  "references" : [ "https://www.cve.org/CVERecord?id=CVE-2021-34866\nhttps://nvd.nist.gov/vuln/detail/CVE-2021-34866\nhttps://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf.git/commit/?id=5b029a32cfe4600f5e10e36b41778506b90fd4de\nhttps://www.zerodayinitiative.com/advisories/ZDI-21-1148/" ],
  "name" : "CVE-2021-34866",
  "mitigation" : {
    "value" : "The default Red Hat Enterprise Linux kernel prevents unprivileged users from being able to use eBPF by the kernel.unprivileged_bpf_disabled sysctl.   This would require a privileged user with CAP_SYS_ADMIN or root to be able to abuse this flaw reducing its attack space.\nFor the Red Hat Enterprise Linux 7 the eBPF for unprivileged users is always disabled.\nFor the Red Hat Enterprise Linux 8 to confirm the current state, inspect the sysctl with the command:\n# cat /proc/sys/kernel/unprivileged_bpf_disabled\nThe setting of 1 would mean that unprivileged users can not use eBPF, mitigating the flaw.\nA kernel update will be required to mitigate the flaw for the root or users with CAP_SYS_ADMIN capabilities.",
    "lang" : "en:us"
  },
  "csaw" : false
}