Nautobot: REST API permits creation of GenericForeignKey references to objects that the user should not be able to reference

Impact

In the case of inter-object references via GenericForeignKey (a pattern allowing an object to reference another object that may belong to one of several different "content types" or database tables), when creating or updating an object containing a GenericForeignKey, Nautobot's REST API failed to enforce user "view" permissions when determining whether a given reference to another object would be valid.

As a concrete example, a user:

• who has permission to create or update ImageAttachment records
• but who lacks permission to view (some or all) Device records
• but who knows (via some other mechanism) the UUID of a specific Device that they do not otherwise have access to

could create via the REST API an ImageAttachment linked to that specific Device.

Other models that use GenericForeignKey and may be writable via the REST API, and hence have a similar vulnerability to ImageAttachment, may include:

• ApprovalWorkflow
• Cable
• ConfigContext
• ContactAssociation
• DataCompliance
• Device
• ExportTemplate
• GraphQLQuery
• Note
• ObjectMetadata
• RelationshipAssociation
• StaticGroupAssociation
• VirtualMachine

Additionally, any Nautobot Apps that provide models with a REST API and use GenericForeignKey may have a similar vulnerability for their models.

Patches

A general-purpose fix has been implemented in Nautobot 2.4.33 and 3.1.2, which ensures correct application of "view" permissions when creating or modifying object references via GenericForeignKey throughout the REST API. Individual models/views/serializers generally will not require any specific code changes to benefit from this fix.

Workarounds

No known workarounds at this time.

References

• 2.4.33 (<a href="https://github.com/nautobot/nautobot/commit/9918bdb9bcf1eb42cda72c344f420a64ef7665f1">patch</a>)
• 3.1.2 (<a href="https://github.com/nautobot/nautobot/commit/36cde7148a207234de6212ec074f321dbc9d1b5b">patch</a>)