diff --git a/src/network/core/http_curl.cpp b/src/network/core/http_curl.cpp
--- a/src/network/core/http_curl.cpp
+++ b/src/network/core/http_curl.cpp
@@ -17,6 +17,7 @@
 #include "../network_internal.h"
 
 #include "http.h"
+#include "http_shared.h"
 
 #include <atomic>
 #include <condition_variable>
@@ -44,6 +45,11 @@ static auto _certificate_directories = {
 };
 #endif /* UNIX */
 
+static std::vector<HTTPThreadSafeCallback *> _http_callbacks;
+static std::vector<HTTPThreadSafeCallback *> _new_http_callbacks;
+static std::mutex _http_callback_mutex;
+static std::mutex _new_http_callback_mutex;
+
 /** Single HTTP request. */
 class NetworkHTTPRequest {
 public:
@@ -59,11 +65,19 @@ public:
 		callback(callback),
 		data(data)
 	{
+		std::lock_guard<std::mutex> lock(_new_http_callback_mutex);
+		_new_http_callbacks.push_back(&this->callback);
 	}
 
-	const std::string uri;        ///< URI to connect to.
-	HTTPCallback *callback;       ///< Callback to send data back on.
-	const std::string data;       ///< Data to send, if any.
+	~NetworkHTTPRequest()
+	{
+		std::lock_guard<std::mutex> lock(_http_callback_mutex);
+		_http_callbacks.erase(std::remove(_http_callbacks.begin(), _http_callbacks.end(), &this->callback), _http_callbacks.end());
+	}
+
+	const std::string uri; ///< URI to connect to.
+	HTTPThreadSafeCallback callback; ///< Callback to send data back on.
+	const std::string data; ///< Data to send, if any.
 };
 
 static std::thread _http_thread;
@@ -92,6 +106,20 @@ static std::string _http_ca_path = "";
 
 /* static */ void NetworkHTTPSocketHandler::HTTPReceive()
 {
+	std::lock_guard<std::mutex> lock(_http_callback_mutex);
+
+	{
+		std::lock_guard<std::mutex> lock_new(_new_http_callback_mutex);
+		if (!_new_http_callbacks.empty()) {
+			/* We delay adding new callbacks, as HandleQueue() below might add a new callback. */
+			_http_callbacks.insert(_http_callbacks.end(), _new_http_callbacks.begin(), _new_http_callbacks.end());
+			_new_http_callbacks.clear();
+		}
+	}
+
+	for (auto &callback : _http_callbacks) {
+		callback->HandleQueue();
+	}
 }
 
 void HttpThread()
@@ -163,11 +191,16 @@ void HttpThread()
 		/* Setup our (C-style) callback function which we pipe back into the callback. */
 		curl_easy_setopt(curl, CURLOPT_WRITEFUNCTION, +[](char *ptr, size_t size, size_t nmemb, void *userdata) -> size_t {
 			Debug(net, 4, "HTTP callback: {} bytes", size * nmemb);
-			HTTPCallback *callback = static_cast<HTTPCallback *>(userdata);
-			callback->OnReceiveData(ptr, size * nmemb);
+			HTTPThreadSafeCallback *callback = static_cast<HTTPThreadSafeCallback *>(userdata);
+
+			/* Copy the buffer out of CURL. OnReceiveData() will free it when done. */
+			std::unique_ptr<char[]> buffer = std::make_unique<char[]>(size * nmemb);
+			memcpy(buffer.get(), ptr, size * nmemb);
+			callback->OnReceiveData(std::move(buffer), size * nmemb);
+
 			return size * nmemb;
 		});
-		curl_easy_setopt(curl, CURLOPT_WRITEDATA, request->callback);
+		curl_easy_setopt(curl, CURLOPT_WRITEDATA, &request->callback);
 
 		/* Create a callback from which we can cancel. Sadly, there is no other
 		 * thread-safe way to do this. If the connection went idle, it can take
@@ -175,10 +208,10 @@ void HttpThread()
 		 * do about this. */
 		curl_easy_setopt(curl, CURLOPT_NOPROGRESS, 0L);
 		curl_easy_setopt(curl, CURLOPT_XFERINFOFUNCTION, +[](void *userdata, curl_off_t /*dltotal*/, curl_off_t /*dlnow*/, curl_off_t /*ultotal*/, curl_off_t /*ulnow*/) -> int {
-			const HTTPCallback *callback = static_cast<HTTPCallback *>(userdata);
-			return (callback->IsCancelled() || _http_thread_exit) ? 1 : 0;
+			const HTTPThreadSafeCallback *callback = static_cast<HTTPThreadSafeCallback *>(userdata);
+			return (callback->cancelled || _http_thread_exit) ? 1 : 0;
 		});
-		curl_easy_setopt(curl, CURLOPT_XFERINFODATA, request->callback);
+		curl_easy_setopt(curl, CURLOPT_XFERINFODATA, &request->callback);
 
 		/* Perform the request. */
 		CURLcode res = curl_easy_perform(curl);
@@ -187,15 +220,18 @@ void HttpThread()
 
 		if (res == CURLE_OK) {
 			Debug(net, 1, "HTTP request succeeded");
-			request->callback->OnReceiveData(nullptr, 0);
+			request->callback.OnReceiveData(nullptr, 0);
 		} else {
 			long status_code = 0;
 			curl_easy_getinfo(curl, CURLINFO_RESPONSE_CODE, &status_code);
 
 			/* No need to be verbose about rate limiting. */
-			Debug(net, (request->callback->IsCancelled() || _http_thread_exit || status_code == HTTP_429_TOO_MANY_REQUESTS) ? 1 : 0, "HTTP request failed: status_code: {}, error: {}", status_code, curl_easy_strerror(res));
-			request->callback->OnFailure();
+			Debug(net, (request->callback.cancelled || _http_thread_exit || status_code == HTTP_429_TOO_MANY_REQUESTS) ? 1 : 0, "HTTP request failed: status_code: {}, error: {}", status_code, curl_easy_strerror(res));
+			request->callback.OnFailure();
 		}
+
+		/* Wait till the callback tells us all data is dequeued. */
+		request->callback.WaitTillEmpty();
 	}
 
 	curl_easy_cleanup(curl);