Public proof of conceptFix available

CVE-2020-8559

Q: Is CVE-2020-8559 actively exploited?

Active exploitation of CVE-2020-8559 has not been confirmed. Its EPSS score was 6.1% on 2026-10-23, the estimated probability of exploitation in the next 30 days.

Q: What is the CVSS score for CVE-2020-8559?

CVE-2020-8559 has a CVSS v3 base score of 6.8 (MEDIUM severity), with vector string CVSS:3.1/AV:N/AC:L/PR:H/UI:R/S:U/C:H/I:H/A:H.

A public proof of concept exists; no exploitation attested.

Published2020-07-22
Fixed in1.18.7 · 1.18.6 · 1.17.9 · 1.16.13
WeaknessCWE-601

Am I affected?

With a domain, we read the version its public headers and pages expose. A distribution build can carry the fix under an older number.

Description

The Kubernetes kube-apiserver in versions v1.6-v1.15, and versions prior to v1.16.13, v1.17.9 and v1.18.6 are vulnerable to an unvalidated redirect on proxied upgrade requests that could allow an attacker to escalate privileges from a node compromise to a full cluster compromise.

Timeline

dates in UTC

2020-07-2214:15CVE publishedNVD

Observed activity

isMalicious corpus · updated 2026-10-23 21:37 UTC

Indicators tagged with this CVE, per day0 indicators over 7 days

Block these indicators

Firewall list (EDL, text): https://api.ismalicious.com/edl/cve/CVE-2020-8559?format=txt
CSV export: https://api.ismalicious.com/edl/cve/CVE-2020-8559?format=csv
TAXII collection of exploited CVEs
The EDL and CSV take an API key on the Pro plan.

Versions per branch

OSV · NVD

Kubernetes

Branch	Affected	Fixed in	Source
1.18	≥ 1.18.0, < 1.18.7	1.18.7	OSV
1.18	≥ 1.18.0, < 1.18.6	1.18.6	NVD
1.17	≥ 1.17.0, < 1.17.9	1.17.9	NVD · OSV
1.16	≥ 1.16.0, < 1.16.13	1.16.13	NVD
1.16	< 1.16.13	1.16.13	OSV
1.x	≥ 1.6.0, ≤ 1.15.0	no fix published	NVD

k8s.io/apimachinery

Branch	Affected	Fixed in	Source
0.18	≥ 0.18.0, < 0.18.7-rc.0	0.18.7-rc.0	OSV
0.18	≥ 0.18.0, < 0.18.7	0.18.7	OSV
0.17	≥ 0.17.0, < 0.17.9	0.17.9	OSV
0.16	< 0.16.13	0.16.13	OSV

as publishedRanges as NVD and OSV publish them; a distribution’s build can be fixed under an older number.

Distribution builds and vendor advisories

Packages from OSV.dev and products from the vendors' CSAF advisories.

version not verifiedVersions not verified: read as OSV.dev and the vendors publish them, not checked against each vendor's release list.

Vendor advisories

CVE-2020-8559 Red Hat Product Security43 products fixed
kubernetes: compromised node could escalate to cluster level privileges
RHSA-2021:0281 Red Hat Product Security3 products fixed
Red Hat Security Advisory: OpenShift Container Platform 4.4.33 bug fix and security update
RHSA-2021:0030 Red Hat Product Security6 products fixed
Red Hat Security Advisory: OpenShift Container Platform 4.4.32 packages and security update
RHSA-2020:5363 Red Hat Product Security24 products fixed
Red Hat Security Advisory: OpenShift Container Platform 3.11.346 security and bug fix update
RHSA-2020:5194 Red Hat Product Security3 products fixed
Red Hat Security Advisory: OpenShift Container Platform 4.5.21 bug fix and security update
RHSA-2020:4298 Red Hat Product Security3 products fixed
Red Hat Security Advisory: OpenShift Container Platform 4.6.1 image security update

1 more advisory

Full record on NVD

Fix

Update Kubernetes to 1.18.7 · 1.18.6 · 1.17.9 · 1.16.13
Vendor fix Red Hat Product Security RHSA-2021:0281 · 3 productsFor OpenShift Container Platform 4.4 see the following documentation, which will be updated shortly for this release, for important instructions on how to upgrade your cluster and fully apply this asynchronous errata update: https://docs.openshift.com/container-platform/4.4/release_notes/ocp-4-4-r…
Vendor fix Red Hat Product Security RHSA-2020:5363 · 24 productsSee the following documentation, which will be updated shortly for release 3.11.346, for important instructions on how to upgrade your cluster and fully apply this asynchronous errata update: https://docs.openshift.com/container-platform/3.11/release_notes/ocp_3_11_release_notes.html This update …
Vendor fix Red Hat Product Security RHSA-2020:5194 · 3 productsFor OpenShift Container Platform 4.5 see the following documentation, which will be updated shortly for this release, for important instructions on how to upgrade your cluster and fully apply this asynchronous errata update: https://docs.openshift.com/container-platform/4.5/release_notes/ocp-4-5-r…
Vendor fix Red Hat Product Security RHSA-2020:4298 · 3 productsFor OpenShift Container Platform 4.6 see the following documentation, which will be updated shortly for this release, for important instructions on how to upgrade your cluster and fully apply this asynchronous errata update: https://docs.openshift.com/container-platform/4.6/release_notes/ocp-4-6-r…
Vendor fix Red Hat Product Security RHBA-2020:4197 · 4 productsFor OpenShift Container Platform 4.6 see the following documentation, which will be updated shortly for this release, for important instructions on how to upgrade your cluster and fully apply this asynchronous errata update: https://docs.openshift.com/container-platform/4.6/release_notes/ocp-4-6-r…
Workaround from the vendor Red Hat Product Security RHSA-2021:0281 · 233 productsNo mitigation is known.

Advisories and patches

github.comPatch

Detection

read 2026-10-23 19:23 UTC

Nuclei template: none so far
Exploit-DB: no entry
Proof-of-concept repositories: 2 repositories, unverifiedtabbysable/POC-2020-8559tdwyer/CVE-2020-8559

Sources

CNACVSS 3.16.4read 2026-10-23
NVDCVSS 3.16.8read 2026-10-23
NVDCVSS 2.06read 2026-10-23
CNAweakness (CWE)CWE-601read 2026-10-23
NVDweakness (CWE)CWE-601read 2026-10-23
FIRST EPSSEPSS score6.1 %2026-10-23
PoC-in-GitHubproof of concept2read 2026-10-23
OSVaffected packages—

Technical details

CVSS v3 Vector: CVSS:3.1/AV:N/AC:L/PR:H/UI:R/S:U/C:H/I:H/A:H
Published: 2020-07-22
Last Modified: 2026-06-17
NVD status: Modified

Frequently asked questions

What is CVE-2020-8559?

Is CVE-2020-8559 actively exploited?

Active exploitation of CVE-2020-8559 has not been confirmed. Its EPSS score was 6.1% on 2026-10-23, the estimated probability of exploitation in the next 30 days.

What is the CVSS score for CVE-2020-8559?

CVE-2020-8559 has a CVSS v3 base score of 6.8 (MEDIUM severity), with vector string CVSS:3.1/AV:N/AC:L/PR:H/UI:R/S:U/C:H/I:H/A:H.

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