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Improper path handling in Kustomization files allows for denial of service

High
hiddeco published GHSA-7pwf-jg34-hxwp May 4, 2022

Package

gomod github.com/fluxcd/flux2 (Go)

Affected versions

< v0.29.0 >= v0.19.0

Patched versions

v0.29.0
gomod github.com/fluxcd/kustomize-controller (Go)
< v0.24.0 >= v0.16.0
v0.29.0

Description

The kustomize-controller enables the use of Kustomize’s functionality when applying Kubernetes declarative state onto a cluster. A malicious user can use a specially crafted kustomization.yaml to cause Denial of Service at controller level.

In multi-tenancy deployments this can lead to multiple tenants not being able to apply their Kustomizations until the malicious kustomization.yaml is removed and the controller restarted.

Impact

Within the affected versions, users with write access to a Flux source are able to craft a malicious kustomization.yaml file which causes the controller to enter an endless loop.

Patches

This vulnerability was fixed in kustomize-controller v0.24.0 and included in flux2 v0.29.0 released on 2022-04-20. The changes introduce better handling of Kustomization files blocking references that could lead to endless loops.

Credits

The Flux engineering team found and patched this vulnerability.

For more information

If you have any questions or comments about this advisory please open an issue in the flux2 repository.

Severity

High

CVSS overall score

This score calculates overall vulnerability severity from 0 to 10 and is based on the Common Vulnerability Scoring System (CVSS).
/ 10

CVSS v3 base metrics

Attack vector
Network
Attack complexity
Low
Privileges required
Low
User interaction
None
Scope
Changed
Confidentiality
None
Integrity
None
Availability
High

CVSS v3 base metrics

Attack vector: More severe the more the remote (logically and physically) an attacker can be in order to exploit the vulnerability.
Attack complexity: More severe for the least complex attacks.
Privileges required: More severe if no privileges are required.
User interaction: More severe when no user interaction is required.
Scope: More severe when a scope change occurs, e.g. one vulnerable component impacts resources in components beyond its security scope.
Confidentiality: More severe when loss of data confidentiality is highest, measuring the level of data access available to an unauthorized user.
Integrity: More severe when loss of data integrity is the highest, measuring the consequence of data modification possible by an unauthorized user.
Availability: More severe when the loss of impacted component availability is highest.
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:N/I:N/A:H

CVE ID

CVE-2022-24878

Weaknesses

Credits