diff --git a/src/platform/datapath_winkernel.c b/src/platform/datapath_winkernel.c
index dc493141f8..15090fb0fd 100644
--- a/src/platform/datapath_winkernel.c
+++ b/src/platform/datapath_winkernel.c
@@ -1695,6 +1695,34 @@ SocketCreateUdp(
         }
     }
 
+    if (Config->CibirIdLength > 0 &&
+        Config->LocalAddress &&
+        Config->LocalAddress->Ipv4.sin_port != 0) {
+        //
+        // When CIBIR is in use, multiple listeners may share the same
+        // port (distinguished by CIBIR ID). Use SO_REUSEADDR instead
+        // of exclusive binding to allow port sharing.
+        //
+        Option = TRUE;
+        Status =
+            CxPlatDataPathSetControlSocket(
+                Binding,
+                WskSetOption,
+                SO_REUSEADDR,
+                SOL_SOCKET,
+                sizeof(Option),
+                &Option);
+        if (QUIC_FAILED(Status)) {
+            QuicTraceEvent(
+                DatapathErrorStatus,
+                "[data][%p] ERROR, %u, %s.",
+                Binding,
+                Status,
+                "Set SO_REUSEADDR");
+            goto Error;
+        }
+    }
+
     IoReuseIrp(&Binding->Irp, STATUS_SUCCESS);
     IoSetCompletionRoutine(
         &Binding->Irp,
diff --git a/src/platform/datapath_winuser.c b/src/platform/datapath_winuser.c
index f0f7b582f0..d6bd0edb27 100644
--- a/src/platform/datapath_winuser.c
+++ b/src/platform/datapath_winuser.c
@@ -1694,7 +1694,34 @@ SocketCreateUdp(
             }
         }
 
-        if (Datapath->Features & CXPLAT_DATAPATH_FEATURE_PORT_RESERVATIONS &&
+        if (Config->CibirIdLength > 0 &&
+            Config->LocalAddress &&
+            Config->LocalAddress->Ipv4.sin_port != 0) {
+            //
+            // When CIBIR is in use, multiple listeners may share the same
+            // port (distinguished by CIBIR ID). Use SO_REUSEADDR instead
+            // of exclusive port reservations to allow port sharing.
+            //
+            Option = TRUE;
+            Result =
+                setsockopt(
+                    SocketProc->Socket,
+                    SOL_SOCKET,
+                    SO_REUSEADDR,
+                    (char*)&Option,
+                    sizeof(Option));
+            if (Result == SOCKET_ERROR) {
+                int WsaError = WSAGetLastError();
+                QuicTraceEvent(
+                    DatapathErrorStatus,
+                    "[data][%p] ERROR, %u, %s.",
+                    Socket,
+                    WsaError,
+                    "Set SO_REUSEADDR");
+                Status = HRESULT_FROM_WIN32(WsaError);
+                goto Error;
+            }
+        } else if (Datapath->Features & CXPLAT_DATAPATH_FEATURE_PORT_RESERVATIONS &&
             Config->LocalAddress &&
             Config->LocalAddress->Ipv4.sin_port != 0) {
             if (i == 0) {
diff --git a/src/test/MsQuicTests.h b/src/test/MsQuicTests.h
index ff2b0297a4..e9f9560ccf 100644
--- a/src/test/MsQuicTests.h
+++ b/src/test/MsQuicTests.h
@@ -402,6 +402,11 @@ void
 QuicTestCibirExtension(
     const CibirExtensionParams& Params
     );
+
+void
+QuicTestCibirSharedPortListeners(
+    const FamilyArgs& Params
+    );
 #endif
 
 void
@@ -1488,6 +1493,10 @@ typedef struct {
     QUIC_CTL_CODE(85, METHOD_BUFFERED, FILE_WRITE_DATA)
     // QUIC_RUN_CIBIR_EXTENSION
 
+#define IOCTL_QUIC_RUN_CIBIR_SHARED_PORT_LISTENERS \
+    QUIC_CTL_CODE(139, METHOD_BUFFERED, FILE_WRITE_DATA)
+    // int - Family
+
 #define IOCTL_QUIC_RUN_STREAM_PRIORITY_INFINITE_LOOP \
     QUIC_CTL_CODE(86, METHOD_BUFFERED, FILE_WRITE_DATA)
 
@@ -1689,7 +1698,7 @@ struct QUIC_RUN_CONNECTION_POOL_CREATE_PARAMS {
     QUIC_CTL_CODE(138, METHOD_BUFFERED, FILE_WRITE_DATA)
     // int - Family
 
-#define QUIC_MAX_IOCTL_FUNC_CODE 138
+#define QUIC_MAX_IOCTL_FUNC_CODE 139
 
 // Generic IOCTL for invoking functions 
 
diff --git a/src/test/bin/quic_gtest.cpp b/src/test/bin/quic_gtest.cpp
index ccba280fcc..1427ebf42f 100644
--- a/src/test/bin/quic_gtest.cpp
+++ b/src/test/bin/quic_gtest.cpp
@@ -1381,6 +1381,15 @@ INSTANTIATE_TEST_SUITE_P(
     WithCibirExtensionParams,
     testing::ValuesIn(WithCibirExtensionParams::Generate()));
 
+TEST_P(WithFamilyArgs, CibirSharedPortListeners) {
+    TestLoggerT<ParamType> Logger("QuicTestCibirSharedPortListeners", GetParam());
+    if (TestingKernelMode) {
+        ASSERT_TRUE(InvokeKernelTest(FUNC(QuicTestCibirSharedPortListeners), GetParam()));
+    } else {
+        QuicTestCibirSharedPortListeners(GetParam());
+    }
+}
+
 #endif
 
 #ifdef QUIC_API_ENABLE_PREVIEW_FEATURES
diff --git a/src/test/bin/winkernel/control.cpp b/src/test/bin/winkernel/control.cpp
index dbf2716fe2..a96543b17c 100644
--- a/src/test/bin/winkernel/control.cpp
+++ b/src/test/bin/winkernel/control.cpp
@@ -539,6 +539,7 @@ size_t QUIC_IOCTL_BUFFER_SIZES[] =
     0,
     0,
     sizeof(INT32),
+    sizeof(INT32),                           // IOCTL_QUIC_RUN_CIBIR_SHARED_PORT_LISTENERS
 };
 
 CXPLAT_STATIC_ASSERT(
@@ -736,6 +737,7 @@ ExecuteTestRequest(
     RegisterTestFunction(QuicTestCustomClientCertificateValidation);
     RegisterTestFunction(QuicTestConnectClientCertificate);
     RegisterTestFunction(QuicTestCibirExtension);
+    RegisterTestFunction(QuicTestCibirSharedPortListeners);
 #ifdef QUIC_API_ENABLE_PREVIEW_FEATURES
 #if QUIC_TEST_DISABLE_VNE_TP_GENERATION
     RegisterTestFunction(QuicTestVNTPOddSize);
diff --git a/src/test/lib/HandshakeTest.cpp b/src/test/lib/HandshakeTest.cpp
index 8e2a4c2d2d..cacbf7e6e6 100644
--- a/src/test/lib/HandshakeTest.cpp
+++ b/src/test/lib/HandshakeTest.cpp
@@ -3935,6 +3935,70 @@ QuicTestCibirExtension(
     TEST_EQUAL(Connection.HandshakeComplete, ShouldConnnect);
 }
 
+void
+QuicTestCibirSharedPortListeners(
+    const FamilyArgs& Params
+    )
+{
+    const int Family = Params.Family;
+
+    //
+    // Two different CIBIR IDs to distinguish multiple listeners on the
+    // same port.
+    //
+    const uint8_t CibirId1[] = { 0 /* offset */, 4, 3, 2, 1 };
+    const uint8_t CibirId2[] = { 0 /* offset */, 5, 6, 7, 8 };
+    const uint8_t CibirIdLength = sizeof(CibirId1);
+
+    MsQuicRegistration Registration(true);
+    TEST_QUIC_SUCCEEDED(Registration.GetInitStatus());
+
+    MsQuicConfiguration ServerConfiguration(Registration, "MsQuicTest", ServerSelfSignedCredConfig);
+    TEST_QUIC_SUCCEEDED(ServerConfiguration.GetInitStatus());
+
+    MsQuicConfiguration ClientConfiguration(Registration, "MsQuicTest", MsQuicCredentialConfig());
+    TEST_QUIC_SUCCEEDED(ClientConfiguration.GetInitStatus());
+
+    QUIC_ADDRESS_FAMILY QuicAddrFamily = (Family == 4) ? QUIC_ADDRESS_FAMILY_INET : QUIC_ADDRESS_FAMILY_INET6;
+
+    //
+    // Start the first CIBIR-enabled listener and let it pick a port.
+    //
+    QuicAddr ServerLocalAddr(QuicAddrFamily);
+    MsQuicAutoAcceptListener Listener1(Registration, ServerConfiguration, MsQuicConnection::NoOpCallback);
+    TEST_QUIC_SUCCEEDED(Listener1.SetCibirId(CibirId1, CibirIdLength));
+    TEST_QUIC_SUCCEEDED(Listener1.Start("MsQuicTest", &ServerLocalAddr.SockAddr));
+    TEST_QUIC_SUCCEEDED(Listener1.GetInitStatus());
+    TEST_QUIC_SUCCEEDED(Listener1.GetLocalAddr(ServerLocalAddr));
+
+    //
+    // Start the second CIBIR-enabled listener on the SAME port.
+    // This exercises the SO_REUSEADDR path added for CIBIR port sharing.
+    //
+    QuicAddr ServerLocalAddr2(QuicAddrFamily);
+    ServerLocalAddr2.SetPort(ServerLocalAddr.GetPort());
+    MsQuicAutoAcceptListener Listener2(Registration, ServerConfiguration, MsQuicConnection::NoOpCallback);
+    TEST_QUIC_SUCCEEDED(Listener2.SetCibirId(CibirId2, CibirIdLength));
+    TEST_QUIC_SUCCEEDED(Listener2.Start("MsQuicTest", &ServerLocalAddr2.SockAddr));
+    TEST_QUIC_SUCCEEDED(Listener2.GetInitStatus());
+
+    //
+    // Verify a client with the first CIBIR ID can connect via the shared port.
+    //
+    MsQuicConnection Connection(Registration);
+    TEST_QUIC_SUCCEEDED(Connection.GetInitStatus());
+    TEST_QUIC_SUCCEEDED(Connection.SetShareUdpBinding());
+    TEST_QUIC_SUCCEEDED(Connection.SetCibirId(CibirId1, CibirIdLength));
+    TEST_QUIC_SUCCEEDED(
+        Connection.Start(
+            ClientConfiguration,
+            ServerLocalAddr.GetFamily(),
+            QUIC_TEST_LOOPBACK_FOR_AF(ServerLocalAddr.GetFamily()),
+            ServerLocalAddr.GetPort()));
+    Connection.HandshakeCompleteEvent.WaitTimeout(TestWaitTimeout);
+    TEST_TRUE(Connection.HandshakeComplete);
+}
+
 #endif // QUIC_API_ENABLE_PREVIEW_FEATURES
 
 void