Capsule is a multi-tenancy and policy-based framework for Kubernetes. From 0.13.0 until 0.13.7, the Tenant update validation in internal/webhook/tenant/validation/forbidden_annotations_regex.go compiles ForbiddenLabels.Regex for both the labels and annotations checks instead of validating ForbiddenAnnotations.Regex. An administrator who can update a Tenant can therefore persist a malformed ForbiddenAnnotations.Regex while leaving the labels expression valid.
Namespace creation or update later passes the stored expression through pkg/api/forbidden_list.go, where regexp.MustCompile can panic during forbidden metadata validation and deny namespace operations for the affected tenant. This issue is fixed in version 0.13.7.
Attack Parameters
Attack Vector
Network
Can be exploited remotely
Attack Complexity
Low
Easy to exploit
Privileges Required
High
Admin privileges needed
User Interaction
None
No user interaction needed
Impact Assessment
Confidentiality
None
No data leak
Integrity
None
No data modification
Availability
High
Complete denial of service
CVSS Vector v3.1
Weakness Type (CWE)
References 4
https://github.com/projectcapsule/capsule/commit/8d89d6865df6f41c7faa22fc9e807a…
security-advisories@github.com
https://github.com/projectcapsule/capsule/pull/1983
security-advisories@github.com
https://github.com/projectcapsule/capsule/releases/tag/v0.13.7
security-advisories@github.com
https://github.com/projectcapsule/capsule/security/advisories/GHSA-gxjc-74v5-3v…
security-advisories@github.com