How severe is CVE-2020-8559?

CVE-2020-8559 has a CVSS score of 6.8/10, rated MEDIUM. Review your exposure and patch according to your risk tolerance.

Which packages are affected by CVE-2020-8559?

CVE-2020-8559 affects the following packages: k8s.io/apimachinery (Go), k8s.io/apimachinery (Go), k8s.io/apimachinery (Go), k8s.io/kubernetes (Go), k8s.io/kubernetes (Go), k8s.io/kubernetes (Go). Ecosystems affected: Go.

How do I fix CVE-2020-8559?

Update k8s.io/apimachinery to 0.16.13 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2020-8559 is resolved across your whole dependency graph.

How do I detect CVE-2020-8559 in my Go dependencies?

Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for k8s.io/apimachinery, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.

How do I mitigate CVE-2020-8559 if there is no patch (or I can't update yet)?

Stop reflecting attacker-controlled destinations: resolve every redirect target against an allowlist of paths or hosts you own, prefer a server-side key over a full URL in the request, and reject absolute URLs entirely where the flow only ever needs a relative one.

Is CVE-2020-8559 actively exploited in the wild?

Yes. There are 6 known exploit references for CVE-2020-8559, including 4 in-the-wild exploitations observed on GitHub and other sources. Treat this as actively exploitable and prioritize patching immediately. All exploit code should only be run in an isolated sandbox environment for research or authorized testing — never against production systems without explicit written authorization.

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

CVE-2020-8559 has an EPSS (Exploit Prediction Scoring System) score of 6.1%, placing it in the 93th percentile of all CVEs. EPSS is maintained by FIRST.org and estimates the probability that a vulnerability will be exploited in the wild within the next 30 days. This score indicates relatively lower exploitation probability, though the CVSS severity should still guide your patching priority.

What type of vulnerability is CVE-2020-8559?

CVE-2020-8559 is classified as Open Redirect (CWE-601). This weakness type describe the underlying flaw category, which helps determine the potential impact and the right class of mitigation.

When was CVE-2020-8559 published, and has it been updated?

CVE-2020-8559 was published on July 22, 2020 and was last updated on October 24, 2026. Advisory data evolves as severity scores, affected ranges, and exploit intelligence are revised — always check the latest version of the advisory before acting.

🐹

🐹 Go

Not in CISA KEV

MEDIUM severity

CVE-2020-8559 — apimachinery

MEDIUMFix: kubernetes/kubernetes#92941

CVE-2020-8559 is a medium-severity (CVSS 6.8) Open Redirect vulnerability in k8s.io/apimachinery. 6 public exploit or proof-of-concept references are indexed, so weaponization risk is real. A fix is available for k8s.io/apimachinery — see the affected versions and patch details below.

Privilege Escalation in Kubernetes

Also known asGHSA-33c5-9fx5-fvjmGO-2024-2748

Published

Jul 22, 2020

Updated

Oct 24, 2026

Affected

6 pkgs

Patched

6 / 6

Exploits

6 known

Exploitation data as of Nov 10, 2026 · OSV.dev, NVD, FIRST.org (EPSS)

EPSS Exploitation Probability

via FIRST.org ↗

6.1%probability of exploitation in next 30 days

Lower Risk0.00%

Lower risk than most CVEs93th percentile — riskier than 93% of all scored CVEsHighest risk

Probability of exploitation in the next 30 days, from FIRST.org EPSS.

How urgent is this, really

Where this sits among everything scored

Real-World Exposure

6 pkgs affected

🐹k8s.io/apimachinery🐹k8s.io/apimachinery🐹k8s.io/apimachinery🐹k8s.io/kubernetes🐹k8s.io/kubernetes🐹k8s.io/kubernetes

Real-time download stats are indexed for npm and PyPI packages. This vulnerability affects Go packages — download data is not available via public APIs for these ecosystems.

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.

Affected Packages

6 total 6 fixed

Ecosystem	Package	Vulnerable range	Fix
🐹Go	`k8s.io/apimachinery`	all versions	0.16.13`go get k8s.io/apimachinery@v0.16.13`
🐹Go	`k8s.io/apimachinery`	≥ 0.17.0&&< 0.17.9	0.17.9`go get k8s.io/apimachinery@v0.17.9`
🐹Go	`k8s.io/apimachinery`	≥ 0.18.0&&< 0.18.7	0.18.7`go get k8s.io/apimachinery@v0.18.7`
🐹Go	`k8s.io/kubernetes`	all versions	1.16.13`go get k8s.io/kubernetes@v1.16.13`
🐹Go	`k8s.io/kubernetes`	≥ 1.17.0&&< 1.17.9	1.17.9`go get k8s.io/kubernetes@v1.17.9`
🐹Go	`k8s.io/kubernetes`	≥ 1.18.0&&< 1.18.7	1.18.7`go get k8s.io/kubernetes@v1.18.7`

Affected Products

1 product · 4 configurations

Application

kuberneteskubernetes

≥ 1.18.0 && ≤ 1.15.0

range

Exploits & PoCs

Research use only. For defensive security, authorized penetration testing, and academic research only. Never execute exploit code against systems without explicit written authorization.

The Kubernetes kube-apiserver in versions v1.6-v1.15, and versions prior…

github.comNVDAug 2020

Report on groups.google.com

groups.google.comNVDAug 2020

Report on github.com

github.comGithubJul 2020

Report on github.com

github.comGithubJul 2020

Detection & mitigation playbook

Open-source dependency

Detect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for k8s.io/apimachinery, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update k8s.io/apimachinery to 0.16.13 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2020-8559 is resolved across your whole dependency graph.
Workarounds
Stop reflecting attacker-controlled destinations: resolve every redirect target against an allowlist of paths or hosts you own, prefer a server-side key over a full URL in the request, and reject absolute URLs entirely where the flow only ever needs a relative one.

Fixing This On Your OS

If you run this on a Linux distribution, patch through your package manager against the distro's own security advisory below — it tracks the exact backported fix for your release, which can ship on a different timeline (and sometimes a different severity) than the upstream project.

Red HatModerate

Kubernetes is embedded in the version of heketi shipped with Red Hat Gluster Storage 3. However, it does not use Kubernetes API server part and only uses client side bits. Hence, this flaw does not affect heketi.

Workaround published by Red Hat

No mitigation is known.

Source: Red Hat security advisory for CVE-2020-8559 (CC BY 4.0)

Product	Fixed in	Advisory
Red Hat OpenShift Container Platform 3.11	`atomic-openshift-0:3.11.346-1.git.0.ea10721.el7`	RHSA-2020:5363
Red Hat OpenShift Container Platform 4.4	`openshift-0:4.4.0-202012052258.p0.git.0.0fd57a4.el7`	RHSA-2021:0030
Red Hat OpenShift Container Platform 4.4	`openshift4/ose-hyperkube:v4.4.0-202101261542.p0`	RHSA-2021:0281
Red Hat OpenShift Container Platform 4.5	`openshift4/ose-hyperkube:v4.5.0-202011211036.p0`	RHSA-2020:5194
Red Hat OpenShift Container Platform 4.6	`openshift-0:4.6.0-202010022112.p0.git.94033.ef41184.el7`	RHBA-2020:4197
Red Hat OpenShift Container Platform 4.6	`openshift4/ose-hyperkube:v4.6.0-202010081843.p0`	RHSA-2020:4298

Frequently Asked Questions

O3 Security · Impact-Aware SCA

Is CVE-2020-8559 in your dependencies?

Find it across Go, including transitive dependencies.

Scan my dependencies How O3 SCA works

CVSS Score

6.8/10CVSS v3 base

Vector breakdown

Attack Vector

Network

Attack Complexity

Low

Privileges Required

High

User Interaction

Required

Scope

Unchanged

Confidentiality

High

Integrity

High

Availability

High

Raw vector

CVSS:3.1/AV:N/AC:L/PR:H/UI:R/S:U/C:H/I:H/A:H

CWE Classification

CWE-601Open Redirect

Weaponization

No Nuclei template or Metasploit module yet. 6 public proof-of-concept references are listed on this page.

OpenSSF Scorecard

Package health score

kubernetes

7.6/10

Maintained10/10

Code-Review10/10

Branch-ProtectionN/A

Assessed Nov 9, 2026

Timeline

Disclosed

Jul 22, 2020

First exploit

Aug 10, 2020

Last updated

Oct 24, 2026

Identifiers

CVE-2020-8559

GHSA-33c5-9fx5-fvjm

GO-2024-2748

References

Advisorysecurity.netapp.com · ntap 20200810 0004 Advisorynvd.nist.gov · CVE 2020 8559 Fixgithub.com Webgithub.com Webbugzilla.redhat.com · show bug.cgi Webgithub.com · CVE 2020 8559 Webgroups.google.com · JAIGG5yNROs Websecurity.netapp.com · ntap 20200810 0004 Packagegithub.com · kubernetes Evidencegroups.google.com · 19nHQ5wkBwAJ

Related vulnerabilities

Also affects apimachinery

This CVE is medium severity; 1 of 1 other CVE affecting apimachinery is rated as high or higher (top: high).

GHSA-74fp-r6jw-h4mp

Also affects kubernetes

This CVE is medium severity; 6 of 7 other CVEs affecting kubernetes are rated as high or higher (top: high).

CVE-2025-13281CVE-2025-5187CVE-2025-4563CVE-2025-1767CVE-2024-9042CVE-2025-0426CVE-2024-10220

Provenance

Sources

OSV.devNVDFIRST.org (EPSS)

Last verifiedOct 24, 2026

CVE-2020-8559 — apimachinery

EPSS Exploitation Probability

How urgent is this, really

Where this sits among everything scored

Real-World Exposure

Description

Affected Packages

Affected Products

Detection & mitigation playbook

Detect

Fix

Workarounds

Fixing This On Your OS

Frequently Asked Questions

Is CVE-2020-8559 in your dependencies?