diff --git a/pkg/attestation/crafter/materials/csaf.go b/pkg/attestation/crafter/materials/csaf.go
index 90dfbce1e..fb09f0bc7 100644
--- a/pkg/attestation/crafter/materials/csaf.go
+++ b/pkg/attestation/crafter/materials/csaf.go
@@ -102,14 +102,22 @@ func (i *CSAFCrafter) Craft(ctx context.Context, filepath string) (*api.Attestat
 	}
 
 	// Validate the CSAF file against the specified category.
-	document, docExists := v.(map[string]interface{})["document"]
-	if docExists {
-		documentMap, docMapOk := document.(map[string]interface{})
-		category, categoryExists := documentMap["category"].(string)
-
-		if docMapOk && categoryExists && category != "" && category != i.category {
-			return nil, fmt.Errorf("invalid CSAF category field in file, expected: %v", i.category)
-		}
+	// First check that the content is a map with a `document` root
+	doc, ok := v.(map[string]interface{})
+	if !ok {
+		return nil, fmt.Errorf("invalid CSAF file: %w", ErrInvalidMaterialType)
+	}
+
+	// Map its content
+	documentMap, ok := doc["document"].(map[string]interface{})
+	if !ok {
+		return nil, fmt.Errorf("invalid CSAF file: %w", ErrInvalidMaterialType)
+	}
+
+	// extract category: not mandatory but if it comes we check it
+	category, categoryExists := documentMap["category"].(string)
+	if categoryExists && category != "" && category != i.category {
+		return nil, fmt.Errorf("invalid CSAF category field in file, expected: %v", i.category)
 	}
 
 	// The validator will try in cascade the different schemas since CSAF specification
diff --git a/pkg/attestation/crafter/materials/csaf_test.go b/pkg/attestation/crafter/materials/csaf_test.go
index db0364417..78cb2da96 100644
--- a/pkg/attestation/crafter/materials/csaf_test.go
+++ b/pkg/attestation/crafter/materials/csaf_test.go
@@ -1,5 +1,5 @@
 //
-// Copyright 2023 The Chainloop Authors.
+// Copyright 2024 The Chainloop Authors.
 //
 // Licensed under the Apache License, Version 2.0 (the "License");
 // you may not use this file except in compliance with the License.
@@ -132,6 +132,24 @@ func TestCSAFCraft(t *testing.T) {
 				Type: contractAPI.CraftingSchema_Material_CSAF_VEX,
 			},
 		},
+		{
+			name:     "empty json array",
+			filePath: "./testdata/empty_array.json",
+			wantErr:  "unexpected material type",
+			schema: &contractAPI.CraftingSchema_Material{
+				Name: "test",
+				Type: contractAPI.CraftingSchema_Material_CSAF_VEX,
+			},
+		},
+		{
+			name:     "empty file",
+			filePath: "./testdata/empty.txt",
+			wantErr:  "unexpected material type",
+			schema: &contractAPI.CraftingSchema_Material{
+				Name: "test",
+				Type: contractAPI.CraftingSchema_Material_CSAF_VEX,
+			},
+		},
 		{
 			name:     "valid json file invalid artifact",
 			filePath: "./testdata/random.json",
diff --git a/pkg/attestation/crafter/materials/materials.go b/pkg/attestation/crafter/materials/materials.go
index 6467fa31a..35f416fe7 100644
--- a/pkg/attestation/crafter/materials/materials.go
+++ b/pkg/attestation/crafter/materials/materials.go
@@ -57,6 +57,10 @@ func uploadAndCraft(ctx context.Context, input *schemaapi.CraftingSchema_Materia
 	}
 	defer result.r.Close()
 
+	if result.size == 0 {
+		return nil, fmt.Errorf("%w: %w", ErrBaseUploadAndCraft, errors.New("file is empty"))
+	}
+
 	l.Debug().Str("filename", result.filename).Str("digest", result.digest).Str("path", artifactPath).
 		Str("size", bytefmt.ByteSize(uint64(result.size))).
 		Str("max_size", bytefmt.ByteSize(uint64(backend.MaxSize))).
diff --git a/pkg/attestation/crafter/materials/testdata/empty_array.json b/pkg/attestation/crafter/materials/testdata/empty_array.json
new file mode 100644
index 000000000..fe51488c7
--- /dev/null
+++ b/pkg/attestation/crafter/materials/testdata/empty_array.json
@@ -0,0 +1 @@
+[]