CVE-2018-20784
CRITICALEPSS 90th pctlDescription
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.
How to fix
This Ubuntu release reached end-of-life on 2023-05-31. Extended security maintenance is available until 2028-04-01.
This Ubuntu release reached end-of-life on 2023-05-31. Extended security maintenance is available until 2028-04-01.
This Ubuntu release reached end-of-life on 2023-05-31. Extended security maintenance is available until 2028-04-01.
This Ubuntu release reached end-of-life on 2023-05-31. Extended security maintenance is available until 2028-04-01.
This Ubuntu release reached end-of-life on 2023-05-31. Extended security maintenance is available until 2028-04-01.
This Ubuntu release reached end-of-life on 2023-05-31. Extended security maintenance is available until 2028-04-01.
This Ubuntu release reached end-of-life on 2023-05-31. Extended security maintenance is available until 2028-04-01.
This Ubuntu release reached end-of-life on 2023-05-31. Extended security maintenance is available until 2028-04-01.
This Ubuntu release reached end-of-life on 2023-05-31. Extended security maintenance is available until 2028-04-01.
This Ubuntu release reached end-of-life on 2023-05-31. Extended security maintenance is available until 2028-04-01.
This Ubuntu release reached end-of-life on 2023-05-31. Extended security maintenance is available until 2028-04-01.
This Ubuntu release reached end-of-life on 2023-05-31. Extended security maintenance is available until 2028-04-01.
This vulnerability affects an unusually large number of packages. The highest-confidence fixes are shown above; the full list is longer. Check the referenced advisories for complete coverage.
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Remediation is compiled from vendor and distribution security advisories. Always confirm against the linked source for your exact version and platform.
CVSS v3 Vector
Exploitability
Impact
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Exploit Intelligence
High risk: more likely to be exploited than 90% of all known CVEs.
References
Related Vulnerabilities
Other CWE-835 vulnerabilities, ordered by exploit likelihood. View all
| CVE | Severity | CVSS | EPSS | Exploited | Fix |
|---|---|---|---|---|---|
| CVE-2020-13935 | High | 7.5 | 87% | - | Fix |
| CVE-2020-36227 | High | 7.5 | 78% | - | Fix |
| CVE-2022-0778 | High | 7.5 | 73% | - | Fix |
| CVE-2024-20353 | High | 8.6 | 71% | KEV | - |
| CVE-2019-14241 | High | 7.5 | 70% | - | - |
| CVE-2017-16944 | High | 7.5 | 63% | - | Fix |
Common questions
How do I fix CVE-2018-20784?
Published advisories record a fix for 57 affected products. The "How to fix" section on this page lists the fixed version and source advisory for each one, so apply the entry matching what you actually run.
Is CVE-2018-20784 being actively exploited?
Not that we know of. CVE-2018-20784 is not in the CISA Known Exploited Vulnerabilities catalog. Its EPSS score of 4.2% is the estimated probability that it will be exploited in the next 30 days. That is higher than 90% of all scored CVEs.
How severe is CVE-2018-20784?
CVE-2018-20784 has a CVSS v3 base score of 9.8, rated critical. CVSS rates the technical impact if the vulnerability is exploited, not how likely that is, so weigh it alongside the exploit-prediction score when you decide what to patch first.
What does CVE-2018-20784 affect?
Published advisories record a fix for linux (Debian), linux (Ubuntu), linux-aws (Ubuntu), linux-aws-hwe (Ubuntu), and 53 more. Only products with a sourced advisory are listed, so treat this as what we can cite rather than a complete inventory.
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This product uses NVD data but is not endorsed or certified by the NVD. EPSS scores courtesy of FIRST.org (https://www.first.org/epss). Source: CISA KEV Catalog. Data as of 2026-06-17.