diff --git a/exceptions/exceptions.hh b/exceptions/exceptions.hh
index 0e11b033aa..28e318ac01 100644
--- a/exceptions/exceptions.hh
+++ b/exceptions/exceptions.hh
@@ -55,13 +55,7 @@ enum class exception_code : int32_t {
     UNPREPARED      = 0x2500
 };
 
-class transport_exception {
-public:
-    virtual exception_code code() const = 0;
-    virtual sstring get_message() const = 0;
-};
-
-class cassandra_exception : public std::exception, public transport_exception {
+class cassandra_exception : public std::exception {
 private:
     exception_code _code;
     sstring _msg;
@@ -71,8 +65,8 @@ public:
         , _msg(std::move(msg))
     { }
     virtual const char* what() const noexcept override { return _msg.begin(); }
-    virtual exception_code code() const override { return _code; }
-    virtual sstring get_message() const override { return what(); }
+    exception_code code() const { return _code; }
+    sstring get_message() const { return what(); }
 };
 
 class request_validation_exception : public cassandra_exception {
diff --git a/transport/protocol_exception.hh b/transport/protocol_exception.hh
index c20f5de52d..95b7933bf3 100644
--- a/transport/protocol_exception.hh
+++ b/transport/protocol_exception.hh
@@ -28,18 +28,11 @@
 
 namespace transport {
 
-class protocol_exception : public std::exception, public exceptions::transport_exception {
-private:
-    exceptions::exception_code _code;
-    sstring _msg;
+class protocol_exception : public exceptions::cassandra_exception {
 public:
     protocol_exception(sstring msg)
-        : _code(exceptions::exception_code::PROTOCOL_ERROR)
-        , _msg(std::move(msg))
+        : exceptions::cassandra_exception{exceptions::exception_code::PROTOCOL_ERROR, std::move(msg)}
     { }
-    virtual const char* what() const noexcept override { return _msg.begin(); }
-    virtual exceptions::exception_code code() const override { return _code; }
-    virtual sstring get_message() const override { return _msg; }
 };
 
 }
diff --git a/transport/server.cc b/transport/server.cc
index b57afda34b..a24a266c94 100644
--- a/transport/server.cc
+++ b/transport/server.cc
@@ -8,6 +8,7 @@
 #include <boost/range/irange.hpp>
 #include <boost/bimap.hpp>
 #include <boost/assign.hpp>
+#include <boost/locale/encoding_utf.hpp>
 
 #include "db/consistency_level.hh"
 #include "core/future-util.hh"
@@ -175,6 +176,14 @@ private:
         }
     }
 
+    void validate_utf8(sstring_view s) {
+        try {
+            boost::locale::conv::utf_to_utf<char>(s.data(), boost::locale::conv::stop);
+        } catch (const boost::locale::conv::conversion_error& ex) {
+            throw transport::protocol_exception("Cannot decode string as UTF8");
+        }
+    }
+
     int8_t read_byte(temporary_buffer<char>& buf);
     int32_t read_int(temporary_buffer<char>& buf);
     int64_t read_long(temporary_buffer<char>& buf);
@@ -677,6 +686,7 @@ sstring cql_server::connection::read_string(temporary_buffer<char>& buf)
     sstring s{buf.begin(), static_cast<size_t>(n)};
     assert(n >= 0);
     buf.trim_front(n);
+    validate_utf8(s);
     return s;
 }
 
@@ -686,6 +696,7 @@ sstring_view cql_server::connection::read_long_string_view(temporary_buffer<char
     check_room(buf, n);
     sstring_view s{buf.begin(), static_cast<size_t>(n)};
     buf.trim_front(n);
+    validate_utf8(s);
     return s;
 }