diff --git a/app/controlplane/pkg/biz/casmapping.go b/app/controlplane/pkg/biz/casmapping.go
index e7bd9dce9..50307d6c8 100644
--- a/app/controlplane/pkg/biz/casmapping.go
+++ b/app/controlplane/pkg/biz/casmapping.go
@@ -21,7 +21,6 @@ import (
 	"slices"
 	"time"
 
-	"github.com/chainloop-dev/chainloop/app/controlplane/pkg/authz"
 	"github.com/chainloop-dev/chainloop/pkg/attestation/renderer/chainloop"
 	"github.com/chainloop-dev/chainloop/pkg/servicelogger"
 	"github.com/go-kratos/kratos/v2/log"
@@ -100,29 +99,9 @@ func (uc *CASMappingUseCase) FindCASMappingForDownloadByUser(ctx context.Context
 		return nil, NewErrInvalidUUID(err)
 	}
 
-	// Load ALL memberships for the given user
-	memberships, err := uc.membershipRepo.ListAllByUser(ctx, userUUID)
+	userOrgs, projectIDs, err := getOrgsAndRBACInfoForUser(ctx, userUUID, uc.membershipRepo, uc.projectsRepo)
 	if err != nil {
-		return nil, fmt.Errorf("failed to list memberships: %w", err)
-	}
-
-	userOrgs := make([]uuid.UUID, 0)
-	// This map holds the list of project IDs by org with RBAC active (user is org "member")
-	projectIDs := make(map[uuid.UUID][]uuid.UUID)
-	for _, m := range memberships {
-		if m.ResourceType == authz.ResourceTypeOrganization {
-			userOrgs = append(userOrgs, m.ResourceID)
-			// If the role in the org is member, we must enable RBAC for projects.
-			if m.Role == authz.RoleOrgMember {
-				// get list of projects in org, and match it with the memberships to build a filter
-				orgProjects, err := getProjectsWithMembership(ctx, uc.projectsRepo, m.ResourceID, memberships)
-				if err != nil {
-					return nil, err
-				}
-				// note that appending an empty slice to a nil slice doesn't change it (it's still nil)
-				projectIDs[m.ResourceID] = orgProjects
-			}
-		}
+		return nil, err
 	}
 
 	mapping, err := uc.FindCASMappingForDownloadByOrg(ctx, digest, userOrgs, projectIDs)
diff --git a/app/controlplane/pkg/biz/membership.go b/app/controlplane/pkg/biz/membership.go
index c60b9a444..383e609c8 100644
--- a/app/controlplane/pkg/biz/membership.go
+++ b/app/controlplane/pkg/biz/membership.go
@@ -344,3 +344,32 @@ func (uc *MembershipUseCase) SetProjectOwner(ctx context.Context, projectID, use
 
 	return nil
 }
+
+func getOrgsAndRBACInfoForUser(ctx context.Context, userID uuid.UUID, mRepo MembershipRepo, pRepo ProjectsRepo) ([]uuid.UUID, map[uuid.UUID][]uuid.UUID, error) {
+	// Load ALL memberships for the given user
+	memberships, err := mRepo.ListAllByUser(ctx, userID)
+	if err != nil {
+		return nil, nil, fmt.Errorf("failed to list memberships: %w", err)
+	}
+
+	userOrgs := make([]uuid.UUID, 0)
+	// This map holds the list of project IDs by org with RBAC active (user is org "member")
+	projectIDs := make(map[uuid.UUID][]uuid.UUID)
+	for _, m := range memberships {
+		if m.ResourceType == authz.ResourceTypeOrganization {
+			userOrgs = append(userOrgs, m.ResourceID)
+			// If the role in the org is member, we must enable RBAC for projects.
+			if m.Role == authz.RoleOrgMember {
+				// get list of projects in org, and match it with the memberships to build a filter
+				orgProjects, err := getProjectsWithMembership(ctx, pRepo, m.ResourceID, memberships)
+				if err != nil {
+					return nil, nil, err
+				}
+				// note that appending an empty slice to a nil slice doesn't change it (it's still nil)
+				projectIDs[m.ResourceID] = orgProjects
+			}
+		}
+	}
+
+	return userOrgs, projectIDs, nil
+}
diff --git a/app/controlplane/pkg/biz/referrer.go b/app/controlplane/pkg/biz/referrer.go
index 421a3b010..e8f3e6c03 100644
--- a/app/controlplane/pkg/biz/referrer.go
+++ b/app/controlplane/pkg/biz/referrer.go
@@ -24,7 +24,6 @@ import (
 	"time"
 
 	conf "github.com/chainloop-dev/chainloop/app/controlplane/internal/conf/controlplane/config/v1"
-	"github.com/chainloop-dev/chainloop/app/controlplane/pkg/authz"
 	v2 "github.com/chainloop-dev/chainloop/pkg/attestation/crafter/api/attestation/v1"
 	"github.com/chainloop-dev/chainloop/pkg/attestation/renderer/chainloop"
 	"github.com/chainloop-dev/chainloop/pkg/servicelogger"
@@ -99,17 +98,21 @@ type StoredReferrer struct {
 	ID        uuid.UUID
 	CreatedAt *time.Time
 	// Fully expanded list of 1-level off references
-	References          []*StoredReferrer
-	OrgIDs, WorkflowIDs []uuid.UUID
+	References                      []*StoredReferrer
+	OrgIDs, WorkflowIDs, ProjectIDs []uuid.UUID
 }
 
+type OrgID = uuid.UUID
+type ProjectID = uuid.UUID
+
 type GetFromRootFilters struct {
 	// RootKind is the kind of the root referrer, i.e ATTESTATION
 	RootKind *string
 	// Wether to filter by visibility or not
 	Public *bool
-	// If not nil, it will be used to filter the result by project
-	ProjectIDs []uuid.UUID
+	// ProjectIDs stores visible projects by org for the requesting user.
+	// If an org entry doesn't exist, it means that RBAC is not applied, hence all projects in that org are visible
+	ProjectIDs map[OrgID][]ProjectID
 }
 
 type GetFromRootFilter func(*GetFromRootFilters)
@@ -120,7 +123,8 @@ func WithKind(kind string) func(*GetFromRootFilters) {
 	}
 }
 
-func WithProjectIDs(projectIDs []uuid.UUID) func(*GetFromRootFilters) {
+// WithVisibleProjectIDs sets visible projects by org for organizations with RBAC enabled for the user (role is OrgMember)
+func WithVisibleProjectIDs(projectIDs map[OrgID][]ProjectID) func(*GetFromRootFilters) {
 	return func(o *GetFromRootFilters) {
 		o.ProjectIDs = projectIDs
 	}
@@ -168,46 +172,24 @@ func (s *ReferrerUseCase) GetFromRootUser(ctx context.Context, digest, rootKind,
 		return nil, NewErrInvalidUUID(err)
 	}
 
-	// We pass the list of organizationsIDs from where to look for the referrer
-	// For now we just pass the list of organizations the user is member of
-	// in the future we will expand this to publicly available orgs and so on.
-	memberships, err := s.membershipRepo.ListAllByUser(ctx, userUUID)
+	userOrgs, projectIDs, err := getOrgsAndRBACInfoForUser(ctx, userUUID, s.membershipRepo, s.projectsRepo)
 	if err != nil {
-		return nil, fmt.Errorf("finding memberships: %w", err)
+		return nil, err
 	}
 
-	orgIDs := make([]uuid.UUID, 0, len(memberships))
-	var projectIDs []uuid.UUID
-	for _, m := range memberships {
-		if m.ResourceType == authz.ResourceTypeOrganization {
-			orgIDs = append(orgIDs, m.ResourceID)
-			// If the role in the org is member, we must enable RBAC for projects.
-			if m.Role == authz.RoleOrgMember {
-				// ensure list is initialized
-				if projectIDs == nil {
-					projectIDs = make([]uuid.UUID, 0)
-				}
-				// get list of projects in org, and match it with the memberships to build a filter
-				orgProjects, err := getProjectsWithMembership(ctx, s.projectsRepo, m.ResourceID, memberships)
-				if err != nil {
-					return nil, err
-				}
-				// note that appending an empty slice to a nil slice doesn't change it (it's still nil)
-				projectIDs = append(projectIDs, orgProjects...)
-			}
-		}
-	}
-
-	return s.GetFromRoot(ctx, digest, rootKind, orgIDs, projectIDs)
+	// We pass the list of organizationsIDs from where to look for the referrer
+	// For now we just pass the list of organizations the user is member of
+	// in the future we will expand this to publicly available orgs and so on.
+	return s.GetFromRoot(ctx, digest, rootKind, userOrgs, projectIDs)
 }
 
-func (s *ReferrerUseCase) GetFromRoot(ctx context.Context, digest, rootKind string, orgIDs []uuid.UUID, projectIDs []uuid.UUID) (*StoredReferrer, error) {
+func (s *ReferrerUseCase) GetFromRoot(ctx context.Context, digest, rootKind string, orgIDs []uuid.UUID, projectIDs map[OrgID][]ProjectID) (*StoredReferrer, error) {
 	filters := make([]GetFromRootFilter, 0)
 	if rootKind != "" {
 		filters = append(filters, WithKind(rootKind))
 	}
 	if projectIDs != nil {
-		filters = append(filters, WithProjectIDs(projectIDs))
+		filters = append(filters, WithVisibleProjectIDs(projectIDs))
 	}
 
 	ref, err := s.repo.GetFromRoot(ctx, digest, orgIDs, filters...)
diff --git a/app/controlplane/pkg/data/referrer.go b/app/controlplane/pkg/data/referrer.go
index b40695e5b..af623d692 100644
--- a/app/controlplane/pkg/data/referrer.go
+++ b/app/controlplane/pkg/data/referrer.go
@@ -18,6 +18,7 @@ package data
 import (
 	"context"
 	"fmt"
+	"slices"
 
 	"github.com/chainloop-dev/chainloop/app/controlplane/pkg/biz"
 	"github.com/chainloop-dev/chainloop/app/controlplane/pkg/data/ent"
@@ -27,6 +28,7 @@ import (
 	"github.com/chainloop-dev/chainloop/app/controlplane/pkg/data/ent/workflow"
 	"github.com/go-kratos/kratos/v2/log"
 	"github.com/google/uuid"
+	"golang.org/x/exp/maps"
 )
 
 type ReferrerRepo struct {
@@ -152,11 +154,6 @@ func (r *ReferrerRepo) GetFromRoot(ctx context.Context, digest string, orgIDs []
 		workflow.DeletedAtIsNil(), workflow.HasOrganizationWith(organization.IDIn(orgIDs...)),
 	}
 
-	// Filter by allowed projects
-	if opts.ProjectIDs != nil {
-		predicateWF = append(predicateWF, workflow.ProjectIDIn(opts.ProjectIDs...))
-	}
-
 	// optionally attaching its visibility
 	if opts.Public != nil {
 		predicateWF = append(predicateWF, workflow.Public(*opts.Public))
@@ -183,8 +180,8 @@ func (r *ReferrerRepo) GetFromRoot(ctx context.Context, digest string, orgIDs []
 	}
 
 	// Find the referrer recursively starting from the root
-	res, err := r.doGet(ctx, refs[0], orgIDs, opts.Public, 0)
-	if err != nil {
+	res, err := r.doGet(ctx, refs[0], orgIDs, opts.ProjectIDs, opts.Public, 0)
+	if err != nil && !biz.IsErrUnauthorized(err) {
 		return nil, fmt.Errorf("failed to get referrer: %w", err)
 	}
 
@@ -196,7 +193,7 @@ func (r *ReferrerRepo) GetFromRoot(ctx context.Context, digest string, orgIDs []
 // we also need to limit this because there might be cycles
 const maxTraverseLevels = 1
 
-func (r *ReferrerRepo) doGet(ctx context.Context, root *ent.Referrer, allowedOrgs []uuid.UUID, public *bool, level int) (*biz.StoredReferrer, error) {
+func (r *ReferrerRepo) doGet(ctx context.Context, root *ent.Referrer, allowedOrgs []uuid.UUID, visibleProjectsMap map[uuid.UUID][]uuid.UUID, public *bool, level int) (*biz.StoredReferrer, error) {
 	// Assemble the referrer to return
 	res := &biz.StoredReferrer{
 		ID:        root.ID,
@@ -213,6 +210,11 @@ func (r *ReferrerRepo) doGet(ctx context.Context, root *ent.Referrer, allowedOrg
 	// add additional information related to the workflows
 	hydrateWorkflowsInfo(root, res)
 
+	// check that, if RBAC is required, the user has visibility on the artifact in at least 1 org/project
+	if visible := isReferrerVisible(res, allowedOrgs, visibleProjectsMap); !visible {
+		return nil, biz.NewErrUnauthorizedStr("referrer not allowed")
+	}
+
 	// Next: We'll find the references recursively up to a max of maxTraverseLevels levels
 	if level >= maxTraverseLevels {
 		return res, nil
@@ -245,17 +247,43 @@ func (r *ReferrerRepo) doGet(ctx context.Context, root *ent.Referrer, allowedOrg
 	for _, reference := range refs {
 		// Call recursively the function
 		// we return all the references
-		ref, err := r.doGet(ctx, reference, allowedOrgs, public, level+1)
-		if err != nil {
+		ref, err := r.doGet(ctx, reference, allowedOrgs, visibleProjectsMap, public, level+1)
+		if err != nil && !biz.IsErrUnauthorized(err) {
 			return nil, fmt.Errorf("failed to get referrer: %w", err)
 		}
 
-		res.References = append(res.References, ref)
+		if ref != nil {
+			res.References = append(res.References, ref)
+		}
 	}
 
 	return res, nil
 }
 
+func isReferrerVisible(ref *biz.StoredReferrer, allowedOrgs []uuid.UUID, visibleProjectsMap map[uuid.UUID][]uuid.UUID) bool {
+	for _, oid := range ref.OrgIDs {
+		if !slices.Contains(allowedOrgs, oid) {
+			// skip check in organizations where the user doesn't have access
+			continue
+		}
+		if visibleProjects, ok := visibleProjectsMap[oid]; ok {
+			// if entry is present, it means we need to apply RBAC
+			// check if visible projects and referrer projects match
+			// by checking if any project is visible by the user
+			for _, pid := range ref.ProjectIDs {
+				if slices.Contains(visibleProjects, pid) {
+					return true
+				}
+			}
+		} else {
+			// if entry is not found in the map, it means that RBAC is not needed for this org, we have finished
+			return true
+		}
+	}
+
+	return false
+}
+
 // hydrate the referrer with the following information:
 // - isPublic: if it has a public workflow associated
 // - workflowIDs: the list of associated workflows
@@ -263,6 +291,7 @@ func (r *ReferrerRepo) doGet(ctx context.Context, root *ent.Referrer, allowedOrg
 func hydrateWorkflowsInfo(root *ent.Referrer, out *biz.StoredReferrer) {
 	isPublic := false
 	workflowIDs := make([]uuid.UUID, 0, len(root.Edges.Workflows))
+	projectIDs := make(map[uuid.UUID]bool, 0)
 	orgIDs := make([]uuid.UUID, 0)
 	orgsMap := make(map[uuid.UUID]struct{}, 0)
 	for _, wf := range root.Edges.Workflows {
@@ -273,9 +302,13 @@ func hydrateWorkflowsInfo(root *ent.Referrer, out *biz.StoredReferrer) {
 		if _, ok := orgsMap[wf.OrganizationID]; !ok {
 			orgIDs = append(orgIDs, wf.OrganizationID)
 		}
+		if _, ok := projectIDs[wf.ProjectID]; !ok {
+			projectIDs[wf.ProjectID] = true
+		}
 		orgsMap[wf.OrganizationID] = struct{}{}
 	}
 
+	out.ProjectIDs = maps.Keys(projectIDs)
 	out.InPublicWorkflow = isPublic
 	out.WorkflowIDs = workflowIDs
 	out.OrgIDs = orgIDs