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kcp allows unauthorized creation and deletion of objects in arbitrary workspaces through APIExport Virtual Workspace

Critical severity GitHub Reviewed Published Mar 20, 2025 in kcp-dev/kcp • Updated Mar 20, 2025

Package

gomod github.com/kcp-dev/kcp (Go)

Affected versions

< 0.26.3

Patched versions

0.26.3

Description

Impact

The APIExport Virtual Workspace can be used to manage objects in workspaces that bind that APIExport for resources defined in the APIExport or specified and accepted via permission claims. This allows an API provider (via their APIExport) scoped down access to workspaces of API consumers to provide their services properly.

The identified vulnerability allows creating or deleting an object via the APIExport VirtualWorkspace in any arbitrary target workspace for pre-existing resources. By design, this should only be allowed when the workspace owner decides to give access to an API provider by creating an APIBinding.

With this vulnerability, it is possible for an attacker to create and delete objects even if none of these requirements are satisfied, i.e. even if there is no APIBinding in that workspace at all or the workspace owner has created an APIBinding, but rejected a permission claim.

Patches

A fix for this issue has been identified and has been published with kcp 0.26.3 and 0.27.0.

Workarounds

For users unable to upgrade to one of the patched versions, the following guidance can be given:

  • Minimise the set of people with apiexport/content sub-resource access to APIExport resources. Be aware that this has to apply to all workspaces to be effective.
  • Filter incoming requests in a reverse proxy with a similar logic as the authorizer added in the referenced pull request.

References

See pull request (kcp-dev/kcp#3338).

References

@embik embik published to kcp-dev/kcp Mar 20, 2025
Published by the National Vulnerability Database Mar 20, 2025
Published to the GitHub Advisory Database Mar 20, 2025
Reviewed Mar 20, 2025
Last updated Mar 20, 2025

Severity

Critical

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
High
Integrity
High
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:C/C:H/I:H/A:N

EPSS score

Exploit Prediction Scoring System (EPSS)

This score estimates the probability of this vulnerability being exploited within the next 30 days. Data provided by FIRST.
(7th percentile)

Weaknesses

CVE ID

CVE-2025-29922

GHSA ID

GHSA-w2rr-38wv-8rrp

Source code

Credits

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