projectcapsule Capsule up to 0.13.5 Validating Webhook configuration.yaml privileges management

Summaryinfo

A vulnerability was found in projectcapsule Capsule up to 0.13.5. It has been rated as very critical. This vulnerability affects unknown code of the file charts/capsule/templates/configuration.yaml of the component Validating Webhook. This manipulation causes privileges management. This vulnerability is handled as CVE-2026-55636. The attack can be initiated remotely. There is not any exploit available. Upgrading the affected component is advised.

Detailsinfo

A vulnerability was found in projectcapsule Capsule up to 0.13.5. It has been declared as very critical. Affected by this vulnerability is an unknown function of the file charts/capsule/templates/configuration.yaml of the component Validating Webhook. The manipulation with an unknown input leads to a privileges management vulnerability. The CWE definition for the vulnerability is CWE-269. The product does not properly assign, modify, track, or check privileges for an actor, creating an unintended sphere of control for that actor. As an impact it is known to affect confidentiality, integrity, and availability. The summary by CVE is:

Capsule is a multi-tenancy and policy-based framework for Kubernetes. From 0.13.0 until 0.13.6, charts/capsule/templates/configuration.yaml configures the validating webhook with namespace/finalize instead of the Kubernetes resource name namespaces/finalize. A user with namespaces/finalize RBAC can send a PUT request to /api/v1/namespaces/{namespace}/finalize, and the singular rule never matches the plural resource, so the validating webhook is not invoked and the user can change the namespace tenant label. matchPolicy: Equivalent does not compensate because it handles API group and version equivalence rather than resource-name errors. This vulnerability is fixed in 0.13.6.

The advisory is shared at github.com. This vulnerability is known as CVE-2026-55636 since 06/17/2026. The exploitation appears to be easy. The attack can be launched remotely. The exploitation needs additional levels of successful authentication. Technical details are known, but no exploit is available. The price for an exploit might be around USD $0-$5k at the moment (estimation calculated on 09/15/2026). MITRE ATT&CK project uses the attack technique T1068 for this issue.

Upgrading to version 0.13.6 eliminates this vulnerability.

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Productinfo

Type

• Project Management Software

Vendor

• projectcapsule

Name

• Capsule

Version

• 0.13.0
• 0.13.1
• 0.13.2
• 0.13.3
• 0.13.4
• 0.13.5

Website

• Product: https://github.com/projectcapsule/capsule/

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