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Kubernetes CVE-2020-8559

MEDIUM
URL Redirection to Untrusted Site (Open Redirect) (CWE-601)
2020-07-22 jordan@liggitt.net
6.8
CVSS 3.1 · NVD
View

Vulnerability Assessment

Weakness
CWE
OWASP Top 10:2025
A01:2025 - Broken Access Control
ASVS 5.0
V3 - Web Frontend Security Redirect URL validation
MITRE ATT&CK

1 technique across 1 tactic: Initial Access

The technique list with ATT&CK links and the kill-chain view is part of the Basic plan and up.

Impact

CVSS score of 6.8 (MEDIUM). Attack characteristics: network attack vector, low complexity, high privileges required, user interaction required. Public proof-of-concept exploit code is available.

Exploit ScenarioDerived

A remote attacker could redirect users to malicious websites via URL manipulation by sending crafted requests to the affected application.

This Month Plan within 30 days. Why: MEDIUM severity (CVSS 4.0-6.9).
Patch available 6.1% exploitation probability (EPSS)

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AnalysisAI

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. Rated medium severity (CVSS 6.8), this vulnerability is remotely exploitable, low attack complexity. Public exploit code available and no vendor patch available.

RemediationAI

No vendor patch is available at time of analysis. Monitor vendor advisories for updates. Validate redirect destinations against an allowlist, avoid using user input in redirect URLs.

Affected Packages

go k8s.io/apimachinery fix: 0.16.13, 0.17.9, 0.18.7-rc.0, 0.18.7
go k8s.io/kubernetes fix: 1.16.13, 1.17.9, 1.18.7

Source: OSV (Open Source Vulnerabilities)

Affects your stack

Affects 2 packages in go

Checking this CVE against your own stacks and servers is part of the Basic plan and up.

Technical ContextAI · show details

This vulnerability is classified as Open Redirect (CWE-601), which allows attackers to redirect users to malicious websites via URL manipulation. 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 products include: Kubernetes.

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  • Exploit and PoC references, threat intelligence from 22 sources

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Severity by source

NVD PRIMARY 6.8 MEDIUM
AV:N/AC:L/PR:H/UI:R/S:U/C:H/I:H/A:H

Primary rating from NVD · only source for this CVE.

CVSS VectorNVD

Attack Vector
Network
Attack Complexity
Low
Privileges Required
High
User Interaction
Required
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High

DescriptionNVD

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.

Threat Intelligence Overview

EPSS Score
6.1%
Top 7% exploitable
Exploit
POC
Public exploit code exists
Data Quality
3 sources
Confidence: Low

How this decision was reached

The engine reads each signal below and applies a fixed list of rules from top to bottom. The first rule that matches sets the recommended action – like a statement, every line is shown.

SignalValue
Severity MEDIUM
CISA KEV No
Public POC Yes
EPSS 6.1%
Patch available Yes
Active threat No
Deciding rule
MEDIUM severity (CVSS 4.0-6.9)
What every action level means
Emergency Immediate action required. Criteria: CRITICAL + in CISA KEV (actively exploited) without patch, OR CRITICAL + EPSS > 30% without patch, OR CRITICAL + active threat signals without patch.
Act Now Prioritize within 24-48h. Criteria: in KEV with patch available, OR CRITICAL + public POC, OR HIGH + EPSS > 10%, OR CRITICAL + active threat, OR any CRITICAL severity.
This Week Schedule remediation this week. Criteria: HIGH severity (CVSS 7.0-8.9). Patch within normal change window.
This Month Plan within 30 days. Criteria: MEDIUM severity (CVSS 4.0-6.9), lower exploitation probability. Include in regular patch cycle.
Monitor Track and reassess. Criteria: LOW severity (CVSS 0.1-3.9), minimal exploitation risk. No immediate action needed.

SSVC AssessmentENISA

SSVC Decision· derived
Scheduled
Exploitation· derived
Poc
System Exposure· derived
Open
Automatable· derived
No
Human Impact· derived
Medium

Priority Score

60
Low Medium High Critical
KEV: 0
EPSS: +6
CVSS: +34
PoC: +20
Weaponized: 0
Threat intel: 0
Gov advisory: 0

Affected Products (CPE)NVD

cpe:2.3:a:kubernetes:kubernetes:*:*:*:*:*:*:*:*
cpe:2.3:a:kubernetes:kubernetes:*:*:*:*:*:*:*:*
cpe:2.3:a:kubernetes:kubernetes:*:*:*:*:*:*:*:*
cpe:2.3:a:kubernetes:kubernetes:*:*:*:*:*:*:*:*
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