Description

A malformed or tampered-with LookupResources Cursor token can cause a panic in the SpiceDB process if it fails to parse. If an attacker were able to make requests to a SpiceDB instance, they could affect its availability.

Reproduction

If you were to take a cursor from one LookupResources call and decode it according to the logic that SpiceDB uses and modify the Sections field to include an invalid relationship string, the process will panic.

Impact

An attacker would need both the ability to create a gRPC connection to your SpiceDB instance and a valid token, or else the ability to pass a cursor token from outside your application through to your SpiceDB instance.

If an attacker had this ability, they could bring down SpiceDB instances, reducing the availability of SpiceDB and any service that depends on it.

Mechanism

The SpiceDB process does not validate the contents of this Sections component of the Cursor message. In affected versions, it uses a parsing function that calls panic if the value cannot be parsed as a relationship.

Fix

This issue was fixed in #2878.

Remediations

• Prevent client control of the optional_cursor field in LookupResources calls
• Upgrade to an unaffected version