# CVE-2020-8559: Privilege escalation from compromised node to cluster > An attacker with node access can exploit an unvalidated redirect in proxied upgrade requests to escalate privileges to full cluster control. - **Severity:** Medium 6.4 (`CVSS:3.1/AV:N/AC:H/PR:H/UI:R/S:U/C:H/I:H/A:H`) - **Exploited in the wild:** Not known - **Login needed:** An administrator - **Attackable:** Over the internet - **Victim action needed:** A user has to click or open something - **Fix available:** Yes - **Published:** 22 Jul 2020 - **Updated:** 16 Sep 2024 - **Also known as:** CLEANSTART-2025-JT47341, CLEANSTART-2026-JX77218, CLEANSTART-2026-RN37949, DEBIAN-CVE-2020-8559, GHSA-33c5-9fx5-fvjm, GO-2024-2748, RHSA-2021:0030 ## What is CVE-2020-8559? CVE-2020-8559 is a medium-severity vulnerability in Kubernetes Kubernetes, published on 22 Jul 2020. An attacker needs administrator access to exploit it, and only if a user opens a file or follows a link. ### Official 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. Weakness: CWE-601 (URL Redirection to Untrusted Site) ## Which versions are affected by CVE-2020-8559? 14 open source packages ship an affected version, including k8s.io/kubernetes and k8s.io/apimachinery. It affects 1 product. | Package | Ecosystem | Affected | Fixed in | | --- | --- | --- | --- | | `k8s.io/kubernetes` | Go | All versions | 1.16.13, 1.17.9, 1.18.7 | | `k8s.io/kubernetes` | Go | All versions | 1.16.13 | | `k8s.io/kubernetes` | Go | All versions | 1.16.13 | | `k8s.io/kubernetes` | Go | From 1.17.0 | 1.17.9 | | `k8s.io/kubernetes` | Go | From 1.17.0 | 1.17.9 | | `k8s.io/kubernetes` | Go | From 1.18.0 | 1.18.7 | | `k8s.io/kubernetes` | Go | From 1.18.0 | 1.18.7 | | `k8s.io/apimachinery` | Go | All versions | 0.16.13, 0.17.9, 0.18.7-rc.0 | | `k8s.io/apimachinery` | Go | All versions | 0.16.13 | | `k8s.io/apimachinery` | Go | All versions | 0.16.13 | | `k8s.io/apimachinery` | Go | From 0.17.0 | 0.17.9 | | `k8s.io/apimachinery` | Go | From 0.17.0 | 0.17.9 | | `k8s.io/apimachinery` | Go | From 0.18.0 | 0.18.7 | | `k8s.io/apimachinery` | Go | From 0.18.0 | 0.18.7 | | `openshift` | Red Hat:openshift:4.4::el7 | All versions | 0:4.4.0-202012052258.p0.git.0.0fd57a4.el7 | | `openshift-hyperkube` | Red Hat:openshift:4.4::el7 | All versions | 0:4.4.0-202012052258.p0.git.0.0fd57a4.el7 | | `openshift` | Red Hat:openshift:4.4::el8 | All versions | 0:4.4.0-202012052258.p0.git.0.0fd57a4.el8 | | `openshift-hyperkube` | Red Hat:openshift:4.4::el8 | All versions | 0:4.4.0-202012052258.p0.git.0.0fd57a4.el8 | Products: Kubernetes Kubernetes. ## How do I fix CVE-2020-8559? Upgrade k8s.io/kubernetes to a fixed version for your release line: 1.16.13, 1.17.9 or 1.18.7. ## Is CVE-2020-8559 being exploited? There is no known exploitation of CVE-2020-8559 in the wild and no public exploit code. Public exploit code: - This is a PoC exploit for CVE-2020-8559 Kubernetes Vulnerability (github_poc): https://github.com/tdwyer/CVE-2020-8559 - Proof of Concept exploit for Kubernetes CVE-2020-8559 (github_poc): https://github.com/tabbysable/POC-2020-8559 ## Other vulnerabilities in Kubernetes Kubernetes - [CVE-2018-1002105](https://insights.sbomify.com/CVE-2018-1002105/): Privilege Escalation in Kubernetes (critical 9.8) - [CVE-2017-1000056](https://insights.sbomify.com/CVE-2017-1000056/): Kubernetes Privilege Escalation (critical 9.8) - [CVE-2016-1906](https://insights.sbomify.com/CVE-2016-1906/): Authorization bypass in Openshift (critical 9.8) - [CVE-2023-3676](https://insights.sbomify.com/CVE-2023-3676/): Kubernetes - Windows nodes - Insufficient input sanitization leads to privilege escalation (high 8.8) - [CVE-2023-3955](https://insights.sbomify.com/CVE-2023-3955/): Kubernetes - Windows nodes - Insufficient input sanitization leads to privilege escalation (high 8.8) ## Fix prompt for AI coding agents ```text Check this codebase for CVE-2020-8559 and fix it if it is affected. What it is: CVE-2020-8559 is a medium-severity vulnerability in Kubernetes Kubernetes, published on 22 Jul 2020. An attacker needs administrator access to exploit it, and only if a user opens a file or follows a link. Exploitation: There is no known exploitation of CVE-2020-8559 in the wild and no public exploit code. Affected packages and fixed versions: - k8s.io/kubernetes (Go): affected all versions; fixed in 1.16.13, 1.17.9, 1.18.7 - k8s.io/kubernetes (Go): affected all versions; fixed in 1.16.13 - k8s.io/kubernetes (Go): affected all versions; fixed in 1.16.13 - k8s.io/kubernetes (Go): affected from 1.17.0; fixed in 1.17.9 - k8s.io/kubernetes (Go): affected from 1.17.0; fixed in 1.17.9 - k8s.io/kubernetes (Go): affected from 1.18.0; fixed in 1.18.7 - k8s.io/kubernetes (Go): affected from 1.18.0; fixed in 1.18.7 - k8s.io/apimachinery (Go): affected all versions; fixed in 0.16.13, 0.17.9, 0.18.7-rc.0 - k8s.io/apimachinery (Go): affected all versions; fixed in 0.16.13 - k8s.io/apimachinery (Go): affected all versions; fixed in 0.16.13 - k8s.io/apimachinery (Go): affected from 0.17.0; fixed in 0.17.9 - k8s.io/apimachinery (Go): affected from 0.17.0; fixed in 0.17.9 Task: 1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies. 2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it. 3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead. 4. Run the tests and summarise what changed and why. 5. If nothing in the project is affected, say so and change nothing. Reference: https://insights.sbomify.com/CVE-2020-8559/ (Markdown: https://insights.sbomify.com/CVE-2020-8559/index.md) ``` ## Sources - CVE record: https://www.cve.org/CVERecord?id=CVE-2020-8559 - NVD: https://nvd.nist.gov/vuln/detail/CVE-2020-8559 - OSV: https://osv.dev/vulnerability/CVE-2020-8559 --- From sbomify Insights: https://insights.sbomify.com/CVE-2020-8559/ Summaries are generated and may contain mistakes; the official description above is the record.