diff --git a/README.md b/README.md
index 561c0165b..99fd8ac6b 100755
--- a/README.md
+++ b/README.md
@@ -146,6 +146,7 @@ For previous versions, please read:
 
 ## V3 changes
 
+* v3.0, 2020-01-05, Always use string instance to avoid crash risk. 3.0.95
 * v3.0, 2020-01-05, For [#460][bug #460], fix ipv6 hostport parsing bug. 3.0.94
 * v3.0, 2020-01-05, For [#460][bug #460], fix ipv6 intranet address filter bug. 3.0.93
 * v3.0, 2020-01-05, For [#1543][bug #1543], use getpeername to retrieve client ip. 3.0.92
diff --git a/trunk/src/app/srs_app_config.cpp b/trunk/src/app/srs_app_config.cpp
index 026ac8801..a0277f3c9 100644
--- a/trunk/src/app/srs_app_config.cpp
+++ b/trunk/src/app/srs_app_config.cpp
@@ -296,7 +296,7 @@ bool srs_config_apply_filter(SrsConfDirective* dvr_apply, SrsRequest* req)
     return false;
 }
 
-string srs_config_bool2switch(const string& sbool)
+string srs_config_bool2switch(string sbool)
 {
     return sbool == "true"? "on":"off";
 }
diff --git a/trunk/src/app/srs_app_config.hpp b/trunk/src/app/srs_app_config.hpp
index 6bc0b4cf2..c9c03e24f 100644
--- a/trunk/src/app/srs_app_config.hpp
+++ b/trunk/src/app/srs_app_config.hpp
@@ -123,7 +123,7 @@ extern bool srs_stream_caster_is_flv(std::string caster);
 extern bool srs_config_apply_filter(SrsConfDirective* dvr_apply, SrsRequest* req);
 
 // Convert bool in str to on/off
-extern std::string srs_config_bool2switch(const std::string& sbool);
+extern std::string srs_config_bool2switch(std::string sbool);
 
 // Parse loaded vhost directives to compatible mode.
 // For exmaple, SRS1/2 use the follow refer style:
diff --git a/trunk/src/app/srs_app_st.cpp b/trunk/src/app/srs_app_st.cpp
index 1e6ae4371..831a0613a 100755
--- a/trunk/src/app/srs_app_st.cpp
+++ b/trunk/src/app/srs_app_st.cpp
@@ -81,7 +81,7 @@ int SrsDummyCoroutine::cid()
 
 _ST_THREAD_CREATE_PFN _pfn_st_thread_create = (_ST_THREAD_CREATE_PFN)st_thread_create;
 
-SrsSTCoroutine::SrsSTCoroutine(const string& n, ISrsCoroutineHandler* h, int cid)
+SrsSTCoroutine::SrsSTCoroutine(string n, ISrsCoroutineHandler* h, int cid)
 {
     name = n;
     handler = h;
diff --git a/trunk/src/app/srs_app_st.hpp b/trunk/src/app/srs_app_st.hpp
index 131ec697c..956e00b42 100644
--- a/trunk/src/app/srs_app_st.hpp
+++ b/trunk/src/app/srs_app_st.hpp
@@ -132,7 +132,7 @@ private:
 public:
     // Create a thread with name n and handler h.
     // @remark User can specify a cid for thread to use, or we will allocate a new one.
-    SrsSTCoroutine(const std::string& n, ISrsCoroutineHandler* h, int cid = 0);
+    SrsSTCoroutine(std::string n, ISrsCoroutineHandler* h, int cid = 0);
     virtual ~SrsSTCoroutine();
 public:
     // Start the thread.
diff --git a/trunk/src/app/srs_app_utility.cpp b/trunk/src/app/srs_app_utility.cpp
index d82dfdf6a..2dc149ddc 100644
--- a/trunk/src/app/srs_app_utility.cpp
+++ b/trunk/src/app/srs_app_utility.cpp
@@ -1157,7 +1157,7 @@ string srs_get_peer_ip(int fd)
     return std::string(saddr);
 }
 
-bool srs_is_boolean(const string& str)
+bool srs_is_boolean(string str)
 {
     return str == "true" || str == "false";
 }
diff --git a/trunk/src/app/srs_app_utility.hpp b/trunk/src/app/srs_app_utility.hpp
index 26da0106d..be7cbced6 100644
--- a/trunk/src/app/srs_app_utility.hpp
+++ b/trunk/src/app/srs_app_utility.hpp
@@ -644,7 +644,7 @@ extern std::string srs_get_peer_ip(int fd);
 //      is_bool("true") == true
 //      is_bool("false") == true
 //      otherwise, false.
-extern bool srs_is_boolean(const std::string& str);
+extern bool srs_is_boolean(std::string str);
 
 // Dump summaries for /api/v1/summaries.
 extern void srs_api_dump_summaries(SrsJsonObject* obj);
diff --git a/trunk/src/core/srs_core.hpp b/trunk/src/core/srs_core.hpp
index b4b9edbd5..0eb763b92 100644
--- a/trunk/src/core/srs_core.hpp
+++ b/trunk/src/core/srs_core.hpp
@@ -27,7 +27,7 @@
 // The version config.
 #define VERSION_MAJOR       3
 #define VERSION_MINOR       0
-#define VERSION_REVISION    94
+#define VERSION_REVISION    95
 
 // The macros generated by configure script.
 #include <srs_auto_headers.hpp>
diff --git a/trunk/src/kernel/srs_kernel_mp4.cpp b/trunk/src/kernel/srs_kernel_mp4.cpp
index 1845a87b2..5cfc5ac9f 100644
--- a/trunk/src/kernel/srs_kernel_mp4.cpp
+++ b/trunk/src/kernel/srs_kernel_mp4.cpp
@@ -110,12 +110,12 @@ void srs_mp4_delimiter_newline(stringstream& ss, SrsMp4DumpContext dc)
     srs_mp4_padding(ss, dc);
 }
 
-int srs_mp4_string_length(const string& v)
+int srs_mp4_string_length(string v)
 {
     return (int)v.length()+1;
 }
 
-void srs_mp4_string_write(SrsBuffer* buf, const string& v)
+void srs_mp4_string_write(SrsBuffer* buf, string v)
 {
     if (!v.empty()) {
         buf->write_bytes((char*)v.data(), (int)v.length());
diff --git a/trunk/src/kernel/srs_kernel_utility.hpp b/trunk/src/kernel/srs_kernel_utility.hpp
index 765a86546..04d386298 100644
--- a/trunk/src/kernel/srs_kernel_utility.hpp
+++ b/trunk/src/kernel/srs_kernel_utility.hpp
@@ -56,7 +56,7 @@ extern std::string srs_dns_resolve(std::string host, int& family);
 
 // Split the host:port to host and port.
 // @remark the hostport format in <host[:port]>, where port is optional.
-extern void srs_parse_hostport(const std::string& hostport, std::string& host, int& port);
+extern void srs_parse_hostport(std::string hostport, std::string& host, int& port);
 
 // Parse the endpoint to ip and port.
 // @remark The hostport format in <[ip:]port>, where ip is default to "0.0.0.0".
diff --git a/trunk/src/protocol/srs_protocol_json.cpp b/trunk/src/protocol/srs_protocol_json.cpp
index 82f099114..c742bb158 100644
--- a/trunk/src/protocol/srs_protocol_json.cpp
+++ b/trunk/src/protocol/srs_protocol_json.cpp
@@ -1731,7 +1731,7 @@ SrsJsonAny* srs_json_parse_tree(json_value* node)
     }
 }
 
-SrsJsonAny* SrsJsonAny::loads(const string& str)
+SrsJsonAny* SrsJsonAny::loads(string str)
 {
     if (str.empty()) {
         return NULL;
diff --git a/trunk/src/protocol/srs_protocol_json.hpp b/trunk/src/protocol/srs_protocol_json.hpp
index cac07a8d5..273b237dc 100644
--- a/trunk/src/protocol/srs_protocol_json.hpp
+++ b/trunk/src/protocol/srs_protocol_json.hpp
@@ -107,7 +107,7 @@ public:
 public:
     // Read json tree from string.
     // @return json object. NULL if error.
-    static SrsJsonAny* loads(const std::string& str);
+    static SrsJsonAny* loads(std::string str);
 };
 
 class SrsJsonObject : public SrsJsonAny
diff --git a/trunk/src/service/srs_service_utility.cpp b/trunk/src/service/srs_service_utility.cpp
index 4d19133f4..108240bdb 100644
--- a/trunk/src/service/srs_service_utility.cpp
+++ b/trunk/src/service/srs_service_utility.cpp
@@ -51,7 +51,7 @@ bool srs_string_is_rtmp(string url)
     return srs_string_starts_with(url, "rtmp://");
 }
 
-bool srs_is_digit_number(const string& str)
+bool srs_is_digit_number(string str)
 {
     if (str.empty()) {
         return false;
diff --git a/trunk/src/service/srs_service_utility.hpp b/trunk/src/service/srs_service_utility.hpp
index c41a86215..ce1acc3ed 100644
--- a/trunk/src/service/srs_service_utility.hpp
+++ b/trunk/src/service/srs_service_utility.hpp
@@ -48,7 +48,7 @@ extern bool srs_string_is_rtmp(std::string url);
 //      is_digit("10e3") === false
 //      is_digit("!1234567890") === false
 //      is_digit("") === false
-extern bool srs_is_digit_number(const std::string& str);
+extern bool srs_is_digit_number(std::string str);
 
 // Get local ip, fill to @param ips
 extern std::vector<std::string>& srs_get_local_ips();
diff --git a/trunk/src/utest/srs_utest_kernel.cpp b/trunk/src/utest/srs_utest_kernel.cpp
index 9868749d5..181bc58b1 100644
--- a/trunk/src/utest/srs_utest_kernel.cpp
+++ b/trunk/src/utest/srs_utest_kernel.cpp
@@ -4254,6 +4254,110 @@ VOID TEST(KernelUtilityTest, CoverTimeUtilityAll)
     _srs_system_time_us_cache -= 300*1000 * 1000 + 1;
     EXPECT_TRUE(srs_update_system_time() > 0);
 
+    if (true) {
+        string host = "127.0.0.1:1935";
+        int port = 0;
+        srs_parse_hostport(host, host, port);
+        EXPECT_EQ(1935, port);
+        EXPECT_STREQ("127.0.0.1", host.c_str());
+    }
+
+    if (true) {
+        string host;
+        int port = 8080;
+        srs_parse_hostport("::1", host, port);
+        EXPECT_EQ(8080, port);
+        EXPECT_STREQ("::1", host.c_str());
+    }
+
+    if (true) {
+        string host;
+        int port = 8080;
+        srs_parse_hostport("::", host, port);
+        EXPECT_EQ(8080, port);
+        EXPECT_STREQ("::", host.c_str());
+    }
+
+    if (true) {
+        string host;
+        int port = 0;
+        srs_parse_hostport("3ffe:dead:beef::1", host, port);
+        EXPECT_EQ(0, port);
+        EXPECT_STREQ("3ffe:dead:beef::1", host.c_str());
+    }
+
+    if (true) {
+        string host;
+        int port = 10;
+        srs_parse_hostport("2001:da8:6000:291:21f:d0ff:fed4:928c", host, port);
+        EXPECT_EQ(10, port);
+        EXPECT_STREQ("2001:da8:6000:291:21f:d0ff:fed4:928c", host.c_str());
+    }
+
+    if (true) {
+        string host;
+        int port = 0;
+        srs_parse_hostport("[2001:da8:6000:291:21f:d0ff:fed4:928c]:167", host, port);
+        EXPECT_EQ(167, port);
+        EXPECT_STREQ("2001:da8:6000:291:21f:d0ff:fed4:928c", host.c_str());
+    }
+
+    if (true) {
+        string host;
+        int port = 0;
+        srs_parse_hostport("[::A.B.C.D]:167", host, port);
+        EXPECT_EQ(167, port);
+        EXPECT_STREQ("::A.B.C.D", host.c_str());
+    }
+
+    if (true) {
+        string host;
+        int port = 0;
+        srs_parse_hostport("::A.B.C.D", host, port);
+        EXPECT_EQ(0, port);
+        EXPECT_STREQ("::A.B.C.D", host.c_str());
+    }
+
+    if (true) {
+        string host;
+        int port = 0;
+        srs_parse_hostport("[::FFFF:A.B.C.D]:167", host, port);
+        EXPECT_EQ(167, port);
+        EXPECT_STREQ("::FFFF:A.B.C.D", host.c_str());
+    }
+
+    if (true) {
+        string host;
+        int port = 0;
+        srs_parse_hostport("[ff00::]:167", host, port);
+        EXPECT_EQ(167, port);
+        EXPECT_STREQ("ff00::", host.c_str());
+    }
+
+    if (true) {
+        string host;
+        int port = 0;
+        srs_parse_hostport("[fe80::a00:27ff:fe84:be2%eth0]:167", host, port);
+        EXPECT_EQ(167, port);
+        EXPECT_STREQ("fe80::a00:27ff:fe84:be2%eth0", host.c_str());
+    }
+
+    if (true) {
+        string host;
+        int port = 0;
+        srs_parse_hostport("::FFFF:A.B.C.D", host, port);
+        EXPECT_EQ(0, port);
+        EXPECT_STREQ("::FFFF:A.B.C.D", host.c_str());
+    }
+
+    if (true) {
+        string host;
+        int port = 8080;
+        srs_parse_hostport("", host, port);
+        EXPECT_EQ(8080, port);
+        EXPECT_STREQ("", host.c_str());
+    }
+
     if (true) {
         string host;
         int port = 8080;