{
  "threat_severity" : "Moderate",
  "public_date" : "2021-03-19T00:00:00Z",
  "bugzilla" : {
    "description" : "kernel: Speculation on pointer arithmetic against bpf_context pointer",
    "id" : "1940627",
    "url" : "https://bugzilla.redhat.com/show_bug.cgi?id=1940627"
  },
  "cvss3" : {
    "cvss3_base_score" : "4.7",
    "cvss3_scoring_vector" : "CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:N/A:N",
    "status" : "verified"
  },
  "cwe" : "CWE-200",
  "details" : [ "An issue was discovered in the Linux kernel before 5.11.8. kernel/bpf/verifier.c performs undesirable out-of-bounds speculation on pointer arithmetic, leading to side-channel attacks that defeat Spectre mitigations and obtain sensitive information from kernel memory, aka CID-f232326f6966. This affects pointer types that do not define a ptr_limit.", "A flaw was found in the Linux kernels eBPF verification code. By default accessing the eBPF verifier is only accessible to privileged users with CAP_SYS_ADMIN.   A local user with the ability to insert eBPF instructions can use the eBPF verifier to abuse a spectre like flaw where they can infer all system memory." ],
  "affected_release" : [ {
    "product_name" : "Red Hat Enterprise Linux 7",
    "release_date" : "2021-06-08T00:00:00Z",
    "advisory" : "RHSA-2021:2316",
    "cpe" : "cpe:/a:redhat:rhel_extras_rt:7",
    "package" : "kernel-rt-0:3.10.0-1160.31.1.rt56.1169.el7"
  }, {
    "product_name" : "Red Hat Enterprise Linux 7",
    "release_date" : "2021-06-08T00:00:00Z",
    "advisory" : "RHSA-2021:2314",
    "cpe" : "cpe:/o:redhat:enterprise_linux:7",
    "package" : "kernel-0:3.10.0-1160.31.1.el7"
  } ],
  "package_state" : [ {
    "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-alt",
    "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" : "Not affected",
    "package_name" : "kernel",
    "cpe" : "cpe:/o:redhat:enterprise_linux:9"
  } ],
  "references" : [ "https://www.cve.org/CVERecord?id=CVE-2020-27170\nhttps://nvd.nist.gov/vuln/detail/CVE-2020-27170" ],
  "name" : "CVE-2020-27170",
  "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
}