diff --git a/go.mod b/go.mod
index a799c3a16..1e223cdab 100644
--- a/go.mod
+++ b/go.mod
@@ -21,7 +21,7 @@ require (
 	github.com/jackc/pgx/v5 v5.10.0
 	github.com/klauspost/cpuid/v2 v2.4.0
 	github.com/miekg/dns v1.1.73
-	github.com/mulgadc/bluebottle v1.18.0
+	github.com/mulgadc/bluebottle v1.18.1-0.20260826044308-1a1e1242c217
 	github.com/mulgadc/northstar v1.18.0
 	github.com/mulgadc/predastore v1.18.0
 	github.com/mulgadc/viperblock v1.18.0
diff --git a/go.sum b/go.sum
index 5e42c2109..8a806ae11 100644
--- a/go.sum
+++ b/go.sum
@@ -1329,6 +1329,8 @@ github.com/muesli/termenv v0.16.0 h1:S5AlUN9dENB57rsbnkPyfdGuWIlkmzJjbFf0Tf5FWUc
 github.com/muesli/termenv v0.16.0/go.mod h1:ZRfOIKPFDYQoDFF4Olj7/QJbW60Ol/kL1pU3VfY/Cnk=
 github.com/mulgadc/bluebottle v1.18.0 h1:aNrogJBz59gJAxCwpERGBC5bGXkSoUCCCBbNvnamuRU=
 github.com/mulgadc/bluebottle v1.18.0/go.mod h1:KkUyzqfKxyI8PvKR27EVqJnVm4BSbajl1Q/u+PQxAYw=
+github.com/mulgadc/bluebottle v1.18.1-0.20260826044308-1a1e1242c217 h1:zRKEFadLkUQxNCK2L3MYSQxRmu4VEEHWTxMwh04Qmeo=
+github.com/mulgadc/bluebottle v1.18.1-0.20260826044308-1a1e1242c217/go.mod h1:KkUyzqfKxyI8PvKR27EVqJnVm4BSbajl1Q/u+PQxAYw=
 github.com/mulgadc/northstar v1.18.0 h1:ksRjIKE6qtrw/ZoYaJh8JRBh+xdnuDw8FsmFLFCiXbg=
 github.com/mulgadc/northstar v1.18.0/go.mod h1:z6iol77R1vsIQyIBc1JQboUPhSJ6eG4bipzfbZZbLEM=
 github.com/mulgadc/predastore v1.18.0 h1:RW1Qw1SM2iYxqi6HaHLv5Qb1h1vhZSO3x6pOhPAb9mw=
diff --git a/spinifex/handlers/iam/roles.go b/spinifex/handlers/iam/roles.go
index 77f11cc86..a74618ad4 100644
--- a/spinifex/handlers/iam/roles.go
+++ b/spinifex/handlers/iam/roles.go
@@ -15,6 +15,7 @@ import (
 	"github.com/aws/aws-sdk-go/service/iam"
 	"github.com/nats-io/nats.go/jetstream"
 
+	iamarn "github.com/mulgadc/bluebottle/pkg/auth"
 	"github.com/mulgadc/spinifex/spinifex/arn"
 	"github.com/mulgadc/spinifex/spinifex/awserrors"
 	"github.com/mulgadc/spinifex/spinifex/kvutil"
@@ -536,17 +537,17 @@ func (s *IAMServiceImpl) GetRolePolicies(accountID, roleName string) ([]PolicyDo
 // stored and round-tripped opaquely so stock EKS tooling that attaches them
 // works without a backing policy document.
 func isAWSManagedPolicyARN(arn string) bool {
-	return strings.HasPrefix(arn, "arn:aws:iam::aws:policy/")
+	return iamarn.IsAWSManagedPolicyARN(arn)
 }
 
 // managedPolicyNameFromARN returns the final path segment of an AWS-managed
 // policy ARN, e.g. .../service-role/AmazonEKS_CNI_Policy -> AmazonEKS_CNI_Policy.
+// Display-only, so an unparseable ARN falls back to itself rather than erroring.
 func managedPolicyNameFromARN(arn string) string {
-	name := strings.TrimPrefix(arn, "arn:aws:iam::aws:policy/")
-	if i := strings.LastIndex(name, "/"); i >= 0 {
-		name = name[i+1:]
+	if _, name, err := iamarn.ParsePolicyARN(arn); err == nil {
+		return name
 	}
-	return name
+	return arn
 }
 
 func (s *IAMServiceImpl) getRole(ctx context.Context, accountID, roleName string) (*Role, error) {
diff --git a/spinifex/handlers/iam/roles_test.go b/spinifex/handlers/iam/roles_test.go
index a1ad16f1a..78053a391 100644
--- a/spinifex/handlers/iam/roles_test.go
+++ b/spinifex/handlers/iam/roles_test.go
@@ -554,6 +554,24 @@ func TestAttachRolePolicy_AWSManagedPolicyNotSeeded(t *testing.T) {
 	assert.Empty(t, out.AttachedPolicies)
 }
 
+func TestAttachRolePolicy_MalformedAWSManagedPolicyRejected(t *testing.T) {
+	svc := setupTestIAMService(t)
+	role := createTestRole(t, svc, "malformed-managed-policy")
+
+	_, err := svc.AttachRolePolicy(testAccountID, &iam.AttachRolePolicyInput{
+		RoleName:  role.RoleName,
+		PolicyArn: aws.String("arn:aws:iam::aws:policy/"),
+	})
+	require.Error(t, err)
+	assert.Contains(t, err.Error(), awserrors.ErrorIAMNoSuchEntity)
+
+	out, err := svc.ListAttachedRolePolicies(testAccountID, &iam.ListAttachedRolePoliciesInput{
+		RoleName: role.RoleName,
+	})
+	require.NoError(t, err)
+	assert.Empty(t, out.AttachedPolicies)
+}
+
 func TestDetachRolePolicy(t *testing.T) {
 	svc := setupTestIAMService(t)
 	role := createTestRole(t, svc, "detach-role")
diff --git a/spinifex/handlers/iam/service_impl.go b/spinifex/handlers/iam/service_impl.go
index c1685d27d..f15423fde 100644
--- a/spinifex/handlers/iam/service_impl.go
+++ b/spinifex/handlers/iam/service_impl.go
@@ -20,6 +20,7 @@ import (
 	"github.com/nats-io/nats.go"
 	"github.com/nats-io/nats.go/jetstream"
 
+	iamarn "github.com/mulgadc/bluebottle/pkg/auth"
 	"github.com/mulgadc/bluebottle/pkg/iampolicy"
 	"github.com/mulgadc/bluebottle/pkg/masterkey"
 	"github.com/mulgadc/spinifex/spinifex/admin"
@@ -1833,13 +1834,12 @@ func (s *IAMServiceImpl) GetUserPolicies(accountID, userName string) ([]PolicyDo
 // ---------------------------------------------------------------------------
 
 func (s *IAMServiceImpl) getPolicyByARN(ctx context.Context, accountID, policyARN string) (*Policy, error) {
-	parts := strings.SplitN(policyARN, ":policy", 2)
-	if len(parts) != 2 || parts[1] == "" {
-		return nil, errors.New(awserrors.ErrorIAMNoSuchEntity)
-	}
-	segments := strings.Split(parts[1], "/")
-	policyName := segments[len(segments)-1]
-	if policyName == "" {
+	_, policyName, err := iamarn.ParsePolicyARN(policyARN)
+	if err != nil {
+		// NoSuchEntity is the response contract, so log the parse reason —
+		// otherwise a malformed ARN is indistinguishable from a missing policy.
+		slog.Debug("getPolicyByARN: unparseable policy ARN",
+			"accountID", accountID, "policyArn", policyARN, "err", err)
 		return nil, errors.New(awserrors.ErrorIAMNoSuchEntity)
 	}
 
diff --git a/spinifex/handlers/iam/service_impl_test.go b/spinifex/handlers/iam/service_impl_test.go
index 99d2390cf..1859e0f8e 100644
--- a/spinifex/handlers/iam/service_impl_test.go
+++ b/spinifex/handlers/iam/service_impl_test.go
@@ -1072,6 +1072,9 @@ func TestGetPolicy_ARNParsingEdgeCases(t *testing.T) {
 		{"trailing slash only", "arn:aws:iam::" + testAccountID + ":policy/"},
 		{"empty after policy", "arn:aws:iam::" + testAccountID + ":policy"},
 		{"no policy segment", "arn:aws:iam::" + testAccountID + ":user/TestARN"},
+		{"policy-backup near miss", "arn:aws:iam::" + testAccountID + ":policy-backup/TestARN"},
+		{"policyset near miss", "arn:aws:iam::" + testAccountID + ":policyset/TestARN"},
+		{"empty account", "arn:aws:iam:::policy/TestARN"},
 	}
 
 	for _, tc := range testCases {
@@ -1079,7 +1082,8 @@ func TestGetPolicy_ARNParsingEdgeCases(t *testing.T) {
 			_, err := svc.GetPolicy(testAccountID, &iam.GetPolicyInput{
 				PolicyArn: aws.String(tc.arn),
 			})
-			assert.Error(t, err, "ARN %q should fail", tc.arn)
+			require.Error(t, err, "ARN %q should fail", tc.arn)
+			assert.Contains(t, err.Error(), awserrors.ErrorIAMNoSuchEntity, "ARN %q", tc.arn)
 		})
 	}
 }