CVE-2021-25737

Holes in EndpointSlice Validation Enable Host Network Hijack

Severity Score

4.8

*CVSS v3.1

Exploit Likelihood

*EPSS

Affected Versions

*CPE

Public Exploits

*Multiple Sources

Exploited in Wild

*KEV

Decision

*SSVC

Descriptions

A security issue was discovered in Kubernetes where a user may be able to redirect pod traffic to private networks on a Node. Kubernetes already prevents creation of Endpoint IPs in the localhost or link-local range, but the same validation was not performed on EndpointSlice IPs.

Se ha detectado un problema de seguridad en Kubernetes en el que un usuario puede ser capaz de redirigir el tráfico del pod a redes privadas en un Nodo. Kubernetes ya previene la creación de IPs de Endpoint en el rango localhost o link-local, pero no se ha llevado a cabo la misma comprobación en las IPs de EndpointSlice.

A security issue was discovered in Kubernetes where an authorized user may be able to redirect traffic to private networks on a Node. An untrusted user could exploit this by creating or modifying EndpointSlices to point to localhost or link-local addresses.

*Credits: John Howard

CVSS Scores

Attack Vector

Network

Attack Complexity

Low

Privileges Required

High

User Interaction

Required

Scope

Changed

Confidentiality

Low

Integrity

Low

Availability

None

Attack Vector

Network

Attack Complexity

Low

Privileges Required

High

User Interaction

None

Scope

Unchanged

Confidentiality

Low

Integrity

None

Availability

None

Attack Vector

Network

Attack Complexity

Medium

Authentication

Single

Confidentiality

Partial

Integrity

Partial

Availability

None

* Common Vulnerability Scoring System

SSVC

Decision:-

Exploitation

Automatable

Tech. Impact

* Organization's Worst-case Scenario

Timeline

2021-01-21 CVE Reserved
2021-07-28 CVE Published
2023-03-30 EPSS Updated
2024-09-16 CVE Updated
---------- Exploited in Wild
---------- KEV Due Date
---------- First Exploit

CWE

CWE-20: Improper Input Validation
CWE-184: Incomplete List of Disallowed Inputs
CWE-601: URL Redirection to Untrusted Site ('Open Redirect')

CAPEC

References (5)

URL	Tag	Source
https://groups.google.com/g/kubernetes-security-announce/c/xAiN3924thY	Mailing List
https://security.netapp.com/advisory/ntap-20211004-0004	Third Party Advisory

URL	Date	SRC

URL	Date	SRC
https://github.com/kubernetes/kubernetes/issues/102106	2021-10-07

URL	Date	SRC
https://access.redhat.com/security/cve/CVE-2021-25737	2021-07-27
https://bugzilla.redhat.com/show_bug.cgi?id=1954917	2021-07-27

Affected Vendors, Products, and Versions

Vendor		Product				Version		Other		Status
Vendor	Product	Version	Other	Status	<-- -->	Vendor	Product	Version	Other	Status
Kubernetes Search vendor "Kubernetes"		Kubernetes Search vendor "Kubernetes" for product "Kubernetes"				>= 1.16.0 < 1.18.19 Search vendor "Kubernetes" for product "Kubernetes" and version " >= 1.16.0 < 1.18.19"		-		Affected
Kubernetes Search vendor "Kubernetes"		Kubernetes Search vendor "Kubernetes" for product "Kubernetes"				>= 1.19.0 < 1.19.10 Search vendor "Kubernetes" for product "Kubernetes" and version " >= 1.19.0 < 1.19.10"		-		Affected
Kubernetes Search vendor "Kubernetes"		Kubernetes Search vendor "Kubernetes" for product "Kubernetes"				>= 1.20.0 < 1.20.7 Search vendor "Kubernetes" for product "Kubernetes" and version " >= 1.20.0 < 1.20.7"		-		Affected
Kubernetes Search vendor "Kubernetes"		Kubernetes Search vendor "Kubernetes" for product "Kubernetes"				1.21.0 Search vendor "Kubernetes" for product "Kubernetes" and version "1.21.0"		-		Affected