Fleet before 4.89.0 contains an SQL injection vulnerability in the activity list endpoints (GET /api/v1/fleet/activities and GET /api/v1/fleet/hosts/{id}/activities). The deprecated cursor-pagination helper appendListOptionsWithCursorToSQL interpolated the caller-supplied sort/order key into the SQL ORDER BY clause without an allowlist, so an authenticated user with read access to Activity could order results by arbitrary columns. The impact is read-only and bounded to columns on the activity_past table that are not otherwise returned in these responses (e.g. details), allowing their values to be inferred through the resulting sort order; there is no write access, privilege escalation, or reachability of node_key or other host-join columns through these endpoints. Fixed in 4.89.0, which removes the deprecated helper and passes the sort column through SanitizeColumn.