Description

An authorization bypass vulnerability in LXD allows an authenticated attacker to bypass target project security restrictions during cross-project instance migrations. When moving an instance cross-project to a different cluster member via POST /1.0/instances/{name} with migration: true, project: <target>, and target: <member>, the destination node skips all project restriction checks because the request arrives as an internal cluster notification. An attacker can exploit this to introduce disallowed instance configurations into a restricted project.

Executive Summary

Technical Details

Mitigations

References

Additional Metadata

{
  "score": "9.9",
  "pubDate": "2026-08-12T20:17:46.897Z",
  "pubdate": "2026-08-12T20:17:46.897Z",
  "executiveSummary": "An authorization bypass vulnerability exists in LXD that enables an authenticated attacker to circumvent target project security restrictions during cross-project instance migrations.\nThe vulnerability affects LXD instances and allows the introduction of disallowed configurations into restricted projects.\nThe flaw stems from improper handling of authorization checks on destination nodes when requests are processed as internal cluster notifications.\nAn attacker must possess authentication credentials and the ability to initiate instance migration operations to successfully exploit this security defect.\nSuccessful exploitation compromises project isolation boundaries within multi-tenant or segmented LXD deployments, potentially leading to unauthorized configuration states and privilege escalation within the affected cluster environment.\nThe risk implication is significant for environments relying on strict project-level isolation to separate distinct administrative domains or security tiers.",
  "technicalDetails": "The vulnerability resides in the request handling logic for cross-project instance migrations within LXD clusters.\nThe vulnerable component is engaged when an API request is submitted via the HTTP endpoint POST /1.0/instances/{name} utilizing the parameters migration: true, project: <target>, and target: <member>.\nThe root cause of the authorization bypass is the failure of the destination cluster member to execute project restriction checks upon receiving the migration payload.\nSpecifically, because the incoming request is internally interpreted or processed as an internal cluster notification rather than a standard client-originated API request targeting the specific project context, security validation routines are omitted.\nThe attack flow proceeds as follows: First, the authenticated attacker initiates a cross-project instance migration targeting a different cluster member and specifying a restricted target project via the vulnerable POST API endpoint. Second, LXD packages and transmits the migration data internally across cluster nodes. Third, upon receipt at the destination node, the request is mishandled as an internal cluster notification, bypassing all standard authorization and project restriction validations. Finally, the instance with disallowed configurations is successfully instantiated and integrated into the restricted target project.\nExploitation requires prior authentication to the LXD API and valid privileges to initiate instance migrations, but no special administrative access to the destination project is enforced due to the logic flaw.\nThe post-exploitation impact includes the successful injection of non-compliant or restricted instance configurations into secure projects, effectively undermining multi-tenant isolation guarantees."
}