diff --git a/components/net/fetch/methods.rs b/components/net/fetch/methods.rs
index 76f640ebb82..3286d1caad3 100644
--- a/components/net/fetch/methods.rs
+++ b/components/net/fetch/methods.rs
@@ -14,7 +14,7 @@ use crossbeam_channel::Sender;
 use devtools_traits::DevtoolsControlMsg;
 use embedder_traits::resources::{self, Resource};
 use headers::{AccessControlExposeHeaders, ContentType, HeaderMapExt};
-use http::header::{self, HeaderMap, HeaderName};
+use http::header::{self, HeaderMap, HeaderName, RANGE};
 use http::{HeaderValue, Method, StatusCode};
 use ipc_channel::ipc;
 use log::{debug, trace, warn};
@@ -47,6 +47,9 @@ use crate::protocols::ProtocolRegistry;
 use crate::request_interceptor::RequestInterceptor;
 use crate::subresource_integrity::is_response_integrity_valid;
 
+const PARTIAL_RESPONSE_TO_NON_RANGE_REQUEST_ERROR: &str = "Refusing to provide partial response\
+from earlier ranged request to API that did not make a range request";
+
 pub type Target<'a> = &'a mut (dyn FetchTaskTarget + Send);
 
 #[derive(Clone, Deserialize, Serialize)]
@@ -484,21 +487,28 @@ pub async fn main_fetch(
             .get_network_error()
             .cloned()
             .map(Response::network_error);
+
+        // Step 15. Let internalResponse be response, if response is a network error;
+        // otherwise response’s internal response.
+        let response_type = response.response_type.clone(); // Needed later after the mutable borrow
         let internal_response = if let Some(error_response) = network_error_response.as_mut() {
             error_response
         } else {
             response.actual_response_mut()
         };
 
-        // Step 16.
+        // Step 16. If internalResponse’s URL list is empty, then set it to a clone of request’s URL list.
         if internal_response.url_list.is_empty() {
             internal_response.url_list.clone_from(&request.url_list)
         }
 
-        // Step 17.
-        // TODO: handle blocking as mixed content.
-        // TODO: handle blocking by content security policy.
-        let blocked_error_response;
+        // Step 19. If response is not a network error and any of the following returns blocked
+        // TODO: * should internalResponse to request be blocked as mixed content
+        // TODO: * should internalResponse to request be blocked by Content Security Policy
+        // * should internalResponse to request be blocked due to its MIME type
+        // * should internalResponse to request be blocked due to nosniff
+        let mut blocked_error_response;
+
         let internal_response = if should_replace_with_nosniff_error {
             // Defer rebinding result
             blocked_error_response =
@@ -513,9 +523,27 @@ pub async fn main_fetch(
             internal_response
         };
 
-        // Step 18.
-        // We check `internal_response` since we did not mutate `response`
-        // in the previous step.
+        // Step 20. If response’s type is "opaque", internalResponse’s status is 206, internalResponse’s
+        // range-requested flag is set, and request’s header list does not contain `Range`, then set
+        // response and internalResponse to a network error.
+        let internal_response = if response_type == ResponseType::Opaque &&
+            internal_response.status.code() == StatusCode::PARTIAL_CONTENT &&
+            internal_response.range_requested &&
+            !request.headers.contains_key(RANGE)
+        {
+            // Defer rebinding result
+            blocked_error_response = Response::network_error(NetworkError::Internal(
+                PARTIAL_RESPONSE_TO_NON_RANGE_REQUEST_ERROR.into(),
+            ));
+            &blocked_error_response
+        } else {
+            internal_response
+        };
+
+        // Step 21. If response is not a network error and either request’s method is `HEAD` or `CONNECT`,
+        // or internalResponse’s status is a null body status, set internalResponse’s body to null and
+        // disregard any enqueuing toward it (if any).
+        // NOTE: We check `internal_response` since we did not mutate `response` in the previous steps.
         let not_network_error = !response_is_network_error && !internal_response.is_network_error();
         if not_network_error &&
             (is_null_body_status(&internal_response.status) ||
diff --git a/components/net/http_loader.rs b/components/net/http_loader.rs
index d92bec2bb5c..8549b11a101 100644
--- a/components/net/http_loader.rs
+++ b/components/net/http_loader.rs
@@ -26,7 +26,7 @@ use headers::{
 };
 use http::header::{
     self, ACCEPT, AUTHORIZATION, CONTENT_ENCODING, CONTENT_LANGUAGE, CONTENT_LOCATION,
-    CONTENT_TYPE, HeaderValue,
+    CONTENT_TYPE, HeaderValue, RANGE,
 };
 use http::{HeaderMap, Method, Request as HyperRequest, StatusCode};
 use http_body_util::combinators::BoxBody;
@@ -1123,7 +1123,7 @@ pub async fn http_redirect_fetch(
     fetch_response
 }
 
-/// [HTTP network or cache fetch](https://fetch.spec.whatwg.org#http-network-or-cache-fetch)
+/// [HTTP network or cache fetch](https://fetch.spec.whatwg.org/#concept-http-network-or-cache-fetch)
 #[async_recursion]
 async fn http_network_or_cache_fetch(
     fetch_params: &mut FetchParams,
@@ -1598,8 +1598,12 @@ async fn http_network_or_cache_fetch(
     }
 
     // TODO(#33616): Step 11. Set response’s URL list to a clone of httpRequest’s URL list.
-    // TODO(#33616): Step 12. If httpRequest’s header list contains `Range`,
-    // then set response’s range-requested flag.
+
+    // Step 12. If httpRequest’s header list contains `Range`, then set response’s range-requested flag.
+    if http_request.headers.contains_key(RANGE) {
+        response.range_requested = true;
+    }
+
     // TODO(#33616): Step 13 Set response’s request-includes-credentials to includeCredentials.
 
     // Step 14. If response’s status is 401, httpRequest’s response tainting is not "cors",
diff --git a/components/net/protocols/blob.rs b/components/net/protocols/blob.rs
index 991cc2a6453..53c609c91a7 100644
--- a/components/net/protocols/blob.rs
+++ b/components/net/protocols/blob.rs
@@ -54,6 +54,7 @@ impl ProtocolHandler for BlobProtocolHander {
         response.status = HttpStatus::default();
 
         if is_range_request {
+            response.range_requested = true;
             partial_content(&mut response);
         }
 
diff --git a/components/shared/net/response.rs b/components/shared/net/response.rs
index 06ca0687da2..f91993ddccb 100644
--- a/components/shared/net/response.rs
+++ b/components/shared/net/response.rs
@@ -120,6 +120,9 @@ pub struct Response {
     /// track network metrics
     #[ignore_malloc_size_of = "Mutex heap size undefined"]
     pub resource_timing: Arc<Mutex<ResourceFetchTiming>>,
+
+    /// <https://fetch.spec.whatwg.org/#concept-response-range-requested-flag>
+    pub range_requested: bool,
 }
 
 impl Response {
@@ -142,6 +145,7 @@ impl Response {
             return_internal: true,
             aborted: Arc::new(AtomicBool::new(false)),
             resource_timing: Arc::new(Mutex::new(resource_timing)),
+            range_requested: false,
         }
     }
 
@@ -175,6 +179,7 @@ impl Response {
             resource_timing: Arc::new(Mutex::new(ResourceFetchTiming::new(
                 ResourceTimingType::Error,
             ))),
+            range_requested: false,
         }
     }