diff --git a/rustfs/src/app/multipart_usecase.rs b/rustfs/src/app/multipart_usecase.rs
index 3275aad5b..de96c0110 100644
--- a/rustfs/src/app/multipart_usecase.rs
+++ b/rustfs/src/app/multipart_usecase.rs
@@ -38,7 +38,7 @@ use rustfs_ecstore::compress::is_compressible;
 use rustfs_ecstore::error::{StorageError, is_err_object_not_found, is_err_version_not_found};
 use rustfs_ecstore::new_object_layer_fn;
 use rustfs_ecstore::set_disk::{MAX_PARTS_COUNT, is_valid_storage_class};
-use rustfs_ecstore::store_api::{CompletePart, MultipartUploadResult, ObjectIO, ObjectOptions, PutObjReader};
+use rustfs_ecstore::store_api::{CompletePart, HTTPRangeSpec, MultipartUploadResult, ObjectIO, ObjectOptions, PutObjReader};
 use rustfs_ecstore::store_api::{MultipartOperations, ObjectOperations};
 use rustfs_filemeta::{ReplicationStatusType, ReplicationType};
 use rustfs_rio::{CompressReader, HashReader, Reader, WarpReader};
@@ -58,6 +58,18 @@ use tokio::sync::RwLock;
 use tokio_util::io::StreamReader;
 use tracing::{info, instrument, warn};
 
+/// Returns InvalidRange error if CopySourceRange end exceeds the source object size.
+/// Used by execute_upload_part_copy to reject out-of-bounds ranges per S3 spec.
+fn validate_copy_source_range_not_exceeds(range_spec: &HTTPRangeSpec, object_size: i64) -> S3Result<()> {
+    if range_spec.end >= object_size {
+        return Err(S3Error::with_message(
+            S3ErrorCode::InvalidRange,
+            "The requested range is not satisfiable".to_string(),
+        ));
+    }
+    Ok(())
+}
+
 #[derive(Clone, Default)]
 pub struct DefaultMultipartUsecase {
     context: Option<Arc<AppContext>>,
@@ -973,6 +985,8 @@ impl DefaultMultipartUsecase {
                 _ => src_info.size,
             };
 
+            validate_copy_source_range_not_exceeds(range_spec, validation_size)?;
+
             range_spec
                 .get_offset_length(validation_size)
                 .map_err(|e| S3Error::with_message(S3ErrorCode::InvalidRange, e.to_string()))?
@@ -1217,6 +1231,44 @@ mod tests {
         assert_eq!(err.code(), &S3ErrorCode::InternalError);
     }
 
+    #[test]
+    fn test_validate_copy_source_range_not_exceeds_returns_invalid_range_when_range_exceeds() {
+        use super::validate_copy_source_range_not_exceeds;
+
+        let range_exceeds = HTTPRangeSpec {
+            is_suffix_length: false,
+            start: 0,
+            end: 21,
+        };
+        let err = validate_copy_source_range_not_exceeds(&range_exceeds, 5).unwrap_err();
+        assert_eq!(err.code(), &S3ErrorCode::InvalidRange);
+        assert!(err.to_string().contains("not satisfiable"));
+    }
+
+    #[test]
+    fn test_validate_copy_source_range_not_exceeds_ok_when_range_valid() {
+        use super::validate_copy_source_range_not_exceeds;
+
+        let range_valid = HTTPRangeSpec {
+            is_suffix_length: false,
+            start: 0,
+            end: 4,
+        };
+        assert!(validate_copy_source_range_not_exceeds(&range_valid, 5).is_ok());
+    }
+
+    #[test]
+    fn test_validate_copy_source_range_not_exceeds_ok_for_suffix_range() {
+        use super::validate_copy_source_range_not_exceeds;
+
+        let range_suffix = HTTPRangeSpec {
+            is_suffix_length: true,
+            start: -5,
+            end: -1,
+        };
+        assert!(validate_copy_source_range_not_exceeds(&range_suffix, 5).is_ok());
+    }
+
     #[tokio::test]
     async fn execute_upload_part_rejects_missing_body() {
         let input = UploadPartInput::builder()
diff --git a/scripts/s3-tests/implemented_tests.txt b/scripts/s3-tests/implemented_tests.txt
index 2737546dd..1e521eda9 100644
--- a/scripts/s3-tests/implemented_tests.txt
+++ b/scripts/s3-tests/implemented_tests.txt
@@ -34,8 +34,9 @@
 # - CORS: Bucket-level CORS configuration, preflight, origin matching
 # - HTTP: 100-continue, multipart abort, tagging in POST Object
 # - DeleteObject: Proper NoSuchBucket for deleted buckets
+# - Multipart Copy: InvalidRange when CopySourceRange exceeds source size
 #
-# Total: 393 tests
+# Total: 394 tests
 
 test_basic_key_count
 test_bucket_create_naming_bad_short_one
@@ -486,3 +487,6 @@ test_100_continue
 test_abort_multipart_upload_not_found
 test_post_object_tags_authenticated_request
 test_object_delete_key_bucket_gone
+
+# Multipart copy range validation
+test_multipart_copy_invalid_range
diff --git a/scripts/s3-tests/non_standard_tests.txt b/scripts/s3-tests/non_standard_tests.txt
index c17dfb9b9..cb0d5d6a2 100644
--- a/scripts/s3-tests/non_standard_tests.txt
+++ b/scripts/s3-tests/non_standard_tests.txt
@@ -224,7 +224,6 @@ test_list_buckets_paginated
 test_list_multipart_upload
 test_list_multipart_upload_owner
 test_multipart_checksum_sha256
-test_multipart_copy_invalid_range
 test_multipart_copy_multiple_sizes
 test_multipart_copy_versioned
 test_multipart_get_part