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capsule-proxy service discloses Namespaces of colliding tenants to owners of different tenants with the same ServiceAccount name

Moderate severity GitHub Reviewed Published Nov 6, 2023 in projectcapsule/capsule-proxy • Updated Nov 7, 2023

Package

gomod github.com/projectcapsule/capsule (Go)

Affected versions

<= 0.4.4

Patched versions

0.4.5
gomod github.com/projectcapsule/capsule-proxy (Go)
<= 0.4.4
0.4.5

Description

Summary

A bug in the RoleBinding reflector used by capsule-proxy gives ServiceAccount tenant owners the right to list Namespaces of other tenants backed by the same owner kind and name.

Details

  • Tenant solar, owned by a ServiceAccount named tenant-owner in the Namespace solar
  • Tenant wind, owned by a ServiceAccount named tenant-owner in the Namespace wind

Please, notice the same ServiceAccount name, although in different namespaces.

The Tenant owner solar would be able to list the namespaces of the Tenant wind and vice-versa, although this is not correct.

The bug introduces an exfiltration vulnerability since allows the listing of Namespace resources of other Tenants, although just in some specific conditions:

  1. capsule-proxy runs with the --disable-caching=false (default value: false)
  2. Tenant owners are ServiceAccount, with the same resource name, but in different Namespaces.

The CVE doesn't allow any privilege escalation on the outer tenant Namespace-scoped resources, since the Kubernetes RBAC is enforcing this.

References

@prometherion prometherion published to projectcapsule/capsule-proxy Nov 6, 2023
Published by the National Vulnerability Database Nov 6, 2023
Published to the GitHub Advisory Database Nov 7, 2023
Reviewed Nov 7, 2023
Last updated Nov 7, 2023

Severity

Moderate

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
Unchanged
Confidentiality
Low
Integrity
None
Availability
None

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:U/C:L/I:N/A:N

EPSS score

0.045%
(15th percentile)

Weaknesses

CVE ID

CVE-2023-46254

GHSA ID

GHSA-6758-979h-249x

Source code

Credits

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