GHSA-gc7j-g665-rxr9

Описание

Summary

Missing validation logic in the storage bucket import logic allows an authenticated user with access to Incus' storage bucket feature to cause the Incus daemon to crash. Repeated use of this issue can be used to keep Incus offline causing a denial of service.

Details

The storage bucket migration subsystem contains a nil-pointer dereference vulnerability that allows an authenticated attacker to crash the daemon during bucket import operations. The vulnerability is present in the backup metadata handling logic, where the daemon processes the index.yaml file from an imported archive and then accesses members of the parsed backup configuration without first verifying that the configuration object was initialized.

In Go, dereferencing a nil pointer triggers a runtime panic. Because CreateBucketFromBackup assumes that srcBackup.Config is populated from the supplied archive, a malicious or malformed index.yaml that omits the config block causes the daemon to dereference a nil pointer and terminate. This results in denial of service on the affected node.

Affected File: https://github.com/lxc/incus/blob/v6.22.0/internal/server/storage/backend.go

Affected Code:

PoC

The following PoC demonstrates that a malformed bucket backup archive with an index.yaml file that omits the config block can trigger a nil-pointer dereference and crash the incusd daemon during bucket import.

Step 1: Create the malformed archive

From a client or workstation with Python available, generate a minimal bucket backup archive whose index.yaml omits the config section.

Commands:

Result:

Step 2: Trigger the vulnerable bucket import path

From an Incus client with permission to import storage buckets, import the crafted archive into any valid storage pool.

Command:

Result:

Step 3: Verify the daemon panic

On the Incus host, inspect the service logs and confirm that the daemon terminated with a nil-pointer panic in the bucket import path.

Command:

Result:

It is recommended to validate that srcBackup.Config is not nil before attempting to access its members. If the required configuration metadata is missing from the archive, the function should return a structured error and abort the operation gracefully rather than allowing a runtime panic to crash the service.

Credit

This issue was discovered and reported by the team at 7asecurity (https://7asecurity.com/)