What is CVE-2018-20784?

CVE-2018-20784 is a critical-severity vulnerability in Linux Kernel, classified under Loop with Unreachable Exit Condition (Infinite Loop). CVSS score: 9.8/10. Published 2019-02-22.

How severe is CVE-2018-20784?

Critical severity. CVSS v3 base score is 9.8 out of 10.

Is CVE-2018-20784 known to be exploited?

1 public proof-of-concept repositories are indexed. Not currently listed in the CISA KEV catalog.

Vulnerability in Linux Kernel

CVE-2018-20784

In the Linux kernel before 4.20.2, kernel/sched/fair.c mishandles leaf cfs_rq's, which allows attackers to cause a denial of service (infinite loop in update_blocked_averages) or possibly have unspecified other impact by inducing a high load.

Published 2019-02-22 · last modified 2026-06-17.

CVSS v3 metric

CVSS v3 base score 9.8 (Critical). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H.

EPSS exploit prediction

EPSS: 0.042 (90.6th percentile), scored 2026-10-01.

Low probability of exploitation in the next 30 days, but still tracked. 91st percentile — 90.6% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS over last 30 days · oldest: 0.042 · newest: 0.042 · change: 0.000

Affected products

Linux Kernel — versions 5.0
Canonical Ubuntu Linux — versions 14.04, 16.04, 18.04
Red Hat Enterprise Linux — versions 8.0
Red Hat Enterprise Linux For Real Time — versions 8

Weakness classification (CWE)

CWE-835 — Loop with Unreachable Exit Condition (Infinite Loop)

Public proof-of-concept exploits

seokjeon/SARD-vs-CVE

References

github.com/torvalds/linux/commit/c40f7d74c741a907cfaeb73a7697081881c497d0 (Patch, Third Party Advisory)
git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit/ (Patch, Vendor Advisory)
cdn.kernel.org/pub/linux/kernel/v4.x/ChangeLog-4.20.2 (Release Notes, Vendor Advisory)
access.redhat.com/errata/RHSA-2019:1959 (vendor-advisory, Third Party Advisory)
access.redhat.com/errata/RHSA-2019:1971 (vendor-advisory, Third Party Advisory)
usn.ubuntu.com/4115-1/ (vendor-advisory, Third Party Advisory)
usn.ubuntu.com/4118-1/ (vendor-advisory, Third Party Advisory)
usn.ubuntu.com/4211-2/ (vendor-advisory, Third Party Advisory)
usn.ubuntu.com/4211-1/ (vendor-advisory, Third Party Advisory)

Frequently asked questions

What is CVE-2018-20784?: CVE-2018-20784 is a critical-severity vulnerability in Linux Kernel, classified under Loop with Unreachable Exit Condition (Infinite Loop). CVSS score: 9.8/10. Published 2019-02-22.
How severe is CVE-2018-20784?: Critical severity. CVSS v3 base score is 9.8 out of 10.
Is CVE-2018-20784 known to be exploited?: 1 public proof-of-concept repositories are indexed. Not currently listed in the CISA KEV catalog.