Capsule Namespace Hijacking via subresource

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Summary

CVECVE-2026-30963
StatePUBLISHED
AssignerGitHub_M
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-06-01 19:16:22 UTC
Updated2026-06-03 20:22:11 UTC
DescriptionCapsule is a multi-tenancy and policy-based framework for Kubernetes. To defend against namespace hijacking achieved through update/patch operations on namespaces, Capsule uses a webhook to validate update requests targeting namespaces. However, in Kubernetes, the namespace/finalize and namespace/status subresource APIs can also modify various fields of a namespace, including the metadata field. Prior to version 0.13.0, the webhook does not define interception rules for these subresources. As a result, if a tenant administrator has permission to modify namespace/status or namespace/finalize, they can successfully perform namespace hijacking. Version 0.13.0 fixes the issue. Another mitigation is to add two subresources (namespaces and snamespaces/status with namespace/finalize within it) to the resources list in the ValidatingWebhookConfiguration rules.

Risk And Classification

Primary CVSS: v3.1 2.7 LOW from [email protected]

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

EPSS: 0.000840000 probability, percentile 0.244370000 (date 2026-06-08)

Problem Types: CWE-20 | NVD-CWE-noinfo | CWE-20 CWE-20: Improper Input Validation

VersionSourceTypeScoreSeverityVector
3.1[email protected]Primary2.7LOWCVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:N/I:L/A:N
3.1[email protected]Secondary3.9LOWCVSS:3.1/AV:N/AC:H/PR:H/UI:R/S:U/C:L/I:L/A:L
3.1CNADECLARED3.9LOWCVSS:3.1/AV:N/AC:H/PR:H/UI:R/S:U/C:L/I:L/A:L

CVSS v3.1 Breakdown

Attack Vector
Network
Attack Complexity
Low
Privileges Required
High
User Interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
Low
Availability
None

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

NVD Known Affected Configurations (CPE 2.3)

TypeVendorProductVersionUpdateEditionLanguage
Application Projectcapsule Capsule All All All All

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Projectcapsule Capsule affected < 0.13.0 Not specified

References

ReferenceSourceLinkTags
github.com/projectcapsule/capsule/releases/tag/v0.13.0 [email protected] github.com Product, Release Notes
github.com/projectcapsule/capsule/security/advisories/GHSA-2ww6-hf35-mfjm 134c704f-9b21-4f2e-91b3-4a467353bcc0 github.com Exploit, Mitigation, Vendor Advisory
CVE Program record CVE.ORG www.cve.org canonical
NVD vulnerability detail NVD nvd.nist.gov canonical, analysis
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