diff --git a/rust/src/http_client.rs b/rust/src/http_client.rs
index e67dae169f..ca4bf1590b 100644
--- a/rust/src/http_client.rs
+++ b/rust/src/http_client.rs
@@ -137,7 +137,7 @@ fn get_runtime<'a>(reactor: &Bound<'a, PyAny>) -> PyResult<PyRef<'a, PyTokioRunt
 static DEFER: OnceCell<PyObject> = OnceCell::new();
 
 /// Access to the `twisted.internet.defer` module.
-fn defer(py: Python<'_>) -> PyResult<&Bound<PyAny>> {
+fn defer(py: Python<'_>) -> PyResult<&Bound<'_, PyAny>> {
     Ok(DEFER
         .get_or_try_init(|| py.import("twisted.internet.defer").map(Into::into))?
         .bind(py))
diff --git a/rust/src/lib.rs b/rust/src/lib.rs
index 0de6898a55..46e22a5cd6 100644
--- a/rust/src/lib.rs
+++ b/rust/src/lib.rs
@@ -11,7 +11,7 @@ pub mod http;
 pub mod http_client;
 pub mod identifier;
 pub mod matrix_const;
-pub mod msc4108v2025_rendezvous;
+pub mod msc4388_rendezvous;
 pub mod push;
 pub mod rendezvous;
 pub mod segmenter;
@@ -55,7 +55,7 @@ fn synapse_rust(py: Python<'_>, m: &Bound<'_, PyModule>) -> PyResult<()> {
     events::register_module(py, m)?;
     http_client::register_module(py, m)?;
     rendezvous::register_module(py, m)?;
-    msc4108v2025_rendezvous::register_module(py, m)?;
+    msc4388_rendezvous::register_module(py, m)?;
     segmenter::register_module(py, m)?;
 
     Ok(())
diff --git a/rust/src/msc4108v2025_rendezvous/mod.rs b/rust/src/msc4388_rendezvous/mod.rs
similarity index 96%
rename from rust/src/msc4108v2025_rendezvous/mod.rs
rename to rust/src/msc4388_rendezvous/mod.rs
index 0535711c63..02204f51d2 100644
--- a/rust/src/msc4108v2025_rendezvous/mod.rs
+++ b/rust/src/msc4388_rendezvous/mod.rs
@@ -58,7 +58,7 @@ fn prepare_headers(headers: &mut HeaderMap) {
 }
 
 #[pyclass]
-struct MSC4108v2025RendezvousHandler {
+struct MSC4388RendezvousHandler {
     clock: PyObject,
     sessions: BTreeMap<Ulid, Session>,
     capacity: usize,
@@ -66,7 +66,7 @@ struct MSC4108v2025RendezvousHandler {
     ttl: Duration,
 }
 
-impl MSC4108v2025RendezvousHandler {
+impl MSC4388RendezvousHandler {
     /// Check the length of the data parameter and throw error if invalid.
     fn check_data_length(&self, data: &str) -> PyResult<()> {
         let data_length = data.len() as u64;
@@ -98,7 +98,7 @@ impl MSC4108v2025RendezvousHandler {
 }
 
 #[pymethods]
-impl MSC4108v2025RendezvousHandler {
+impl MSC4388RendezvousHandler {
     #[new]
     #[pyo3(signature = (homeserver, /, capacity=100, max_content_length=4*1024, eviction_interval=60*1000, ttl=2*60*1000))]
     fn new(
@@ -324,7 +324,7 @@ impl MSC4108v2025RendezvousHandler {
             return Err(SynapseError::new(
                 StatusCode::CONFLICT,
                 "sequence_token does not match".to_owned(),
-                "IO_ELEMENT_MSC4108_CONCURRENT_WRITE",
+                "IO_ELEMENT_MSC4388_CONCURRENT_WRITE",
                 None,
                 Some(headers),
             ));
@@ -365,9 +365,9 @@ impl MSC4108v2025RendezvousHandler {
 }
 
 pub fn register_module(py: Python<'_>, m: &Bound<'_, PyModule>) -> PyResult<()> {
-    let child_module = PyModule::new(py, "msc4108v2025_rendezvous")?;
+    let child_module = PyModule::new(py, "msc4388_rendezvous")?;
 
-    child_module.add_class::<MSC4108v2025RendezvousHandler>()?;
+    child_module.add_class::<MSC4388RendezvousHandler>()?;
 
     m.add_submodule(&child_module)?;
 
@@ -375,7 +375,7 @@ pub fn register_module(py: Python<'_>, m: &Bound<'_, PyModule>) -> PyResult<()>
     // synapse.synapse_rust import rendezvous` work.
     py.import("sys")?
         .getattr("modules")?
-        .set_item("synapse.synapse_rust.msc4108v2025_rendezvous", child_module)?;
+        .set_item("synapse.synapse_rust.msc4388_rendezvous", child_module)?;
 
     Ok(())
 }
diff --git a/rust/src/msc4108v2025_rendezvous/session.rs b/rust/src/msc4388_rendezvous/session.rs
similarity index 100%
rename from rust/src/msc4108v2025_rendezvous/session.rs
rename to rust/src/msc4388_rendezvous/session.rs
diff --git a/synapse/config/experimental.py b/synapse/config/experimental.py
index 2fff862e44..b266bb174f 100644
--- a/synapse/config/experimental.py
+++ b/synapse/config/experimental.py
@@ -548,25 +548,23 @@ class ExperimentalConfig(Config):
                 ("experimental", "msc4108_delegation_endpoint"),
             )
 
-        # MSC4108: Mechanism to allow OAuth 2.0 API sign in and E2EE set up via QR code - 2025 version:
-        msc4108v2025_mode = experimental.get("msc4108v2025_mode", "off")
+        # MSC4388: Secure out-of-band channel for sign in with QR:
+        msc4388_mode = experimental.get("msc4388_mode", "off")
 
-        if ["off", "public", "authenticated"].count(msc4108v2025_mode) != 1:
+        if ["off", "public", "authenticated"].count(msc4388_mode) != 1:
             raise ConfigError(
-                "msc4108v2025_mode must be one of 'off', 'public' or 'authenticated'",
-                ("experimental", "msc4108v2025_mode"),
+                "msc4388_mode must be one of 'off', 'public' or 'authenticated'",
+                ("experimental", "msc4388_mode"),
             )
-        self.msc4108v2025_enabled: bool = msc4108v2025_mode != "off"
-        self.msc4108v2025_requires_authentication: bool = (
-            msc4108v2025_mode == "authenticated"
-        )
+        self.msc4388_enabled: bool = msc4388_mode != "off"
+        self.msc4388_requires_authentication: bool = msc4388_mode == "authenticated"
 
-        if self.msc4108v2025_enabled and not (
+        if self.msc4388_enabled and not (
             config.get("matrix_authentication_service") or {}
         ).get("enabled", False):
             raise ConfigError(
-                "MSC4108 2025 version requires matrix_authentication_service to be enabled",
-                ("experimental", "msc4108v2025_enabled"),
+                "MSC4388 requires matrix_authentication_service to be enabled",
+                ("experimental", "msc4388_enabled"),
             )
 
         # MSC4133: Custom profile fields
diff --git a/synapse/rest/client/rendezvous.py b/synapse/rest/client/rendezvous.py
index 8baab56a4b..388942711d 100644
--- a/synapse/rest/client/rendezvous.py
+++ b/synapse/rest/client/rendezvous.py
@@ -68,17 +68,17 @@ class MSC4108RendezvousServlet(RestServlet):
         self._handler.handle_post(request)
 
 
-class MSC4108v2025CreateRendezvousServlet(RestServlet):
+class MSC4388CreateRendezvousServlet(RestServlet):
     PATTERNS = client_patterns(
-        "/io.element.msc4108/rendezvous$", releases=[], v1=False, unstable=True
+        "/io.element.msc4388/rendezvous$", releases=[], v1=False, unstable=True
     )
 
     def __init__(self, hs: "HomeServer") -> None:
         super().__init__()
-        self._handler = hs.get_msc4108v2025_rendezvous_handler()
+        self._handler = hs.get_msc4388_rendezvous_handler()
         self.auth = hs.get_auth()
         self.require_authentication = (
-            hs.config.experimental.msc4108v2025_requires_authentication
+            hs.config.experimental.msc4388_requires_authentication
         )
 
     async def on_POST(self, request: SynapseRequest) -> None:
@@ -88,9 +88,9 @@ class MSC4108v2025CreateRendezvousServlet(RestServlet):
         self._handler.handle_post(request)
 
 
-class MSC4108v2025UpdateRendezvousServlet(RestServlet):
+class MSC4388UpdateRendezvousServlet(RestServlet):
     PATTERNS = client_patterns(
-        "/io.element.msc4108/rendezvous/(?P<rendezvous_id>[^/]+)$",
+        "/io.element.msc4388/rendezvous/(?P<rendezvous_id>[^/]+)$",
         releases=[],
         v1=False,
         unstable=True,
@@ -98,7 +98,7 @@ class MSC4108v2025UpdateRendezvousServlet(RestServlet):
 
     def __init__(self, hs: "HomeServer") -> None:
         super().__init__()
-        self._handler = hs.get_msc4108v2025_rendezvous_handler()
+        self._handler = hs.get_msc4388_rendezvous_handler()
 
     def on_GET(self, request: SynapseRequest, rendezvous_id: str) -> None:
         self._handler.handle_get(request, rendezvous_id)
@@ -117,6 +117,6 @@ def register_servlets(hs: "HomeServer", http_server: HttpServer) -> None:
     if hs.config.experimental.msc4108_delegation_endpoint is not None:
         MSC4108DelegationRendezvousServlet(hs).register(http_server)
 
-    if hs.config.experimental.msc4108v2025_enabled:
-        MSC4108v2025CreateRendezvousServlet(hs).register(http_server)
-        MSC4108v2025UpdateRendezvousServlet(hs).register(http_server)
+    if hs.config.experimental.msc4388_enabled:
+        MSC4388CreateRendezvousServlet(hs).register(http_server)
+        MSC4388UpdateRendezvousServlet(hs).register(http_server)
diff --git a/synapse/rest/client/versions.py b/synapse/rest/client/versions.py
index 590582bee7..db00a3ecb3 100644
--- a/synapse/rest/client/versions.py
+++ b/synapse/rest/client/versions.py
@@ -169,10 +169,8 @@ class VersionsRestServlet(RestServlet):
                             is not None
                         )
                     ),
-                    # MSC4108: Mechanism to allow OIDC sign in and E2EE set up via QR code - 2025 version
-                    "io.element.msc4108": (
-                        self.config.experimental.msc4108v2025_enabled
-                    ),
+                    # MSC4388: Secure out-of-band channel for sign in with QR
+                    "io.element.msc4388": (self.config.experimental.msc4388_enabled),
                     # MSC4140: Delayed events
                     "org.matrix.msc4140": bool(self.config.server.max_event_delay_ms),
                     # Simplified sliding sync
diff --git a/synapse/server.py b/synapse/server.py
index 990e4d704a..c174c767dd 100644
--- a/synapse/server.py
+++ b/synapse/server.py
@@ -170,7 +170,7 @@ from synapse.state import StateHandler, StateResolutionHandler
 from synapse.storage import Databases
 from synapse.storage.controllers import StorageControllers
 from synapse.streams.events import EventSources
-from synapse.synapse_rust.msc4108v2025_rendezvous import MSC4108v2025RendezvousHandler
+from synapse.synapse_rust.msc4388_rendezvous import MSC4388RendezvousHandler
 from synapse.synapse_rust.rendezvous import RendezvousHandler
 from synapse.types import DomainSpecificString, ISynapseReactor
 from synapse.util import SYNAPSE_VERSION
@@ -1158,8 +1158,8 @@ class HomeServer(metaclass=abc.ABCMeta):
         return RendezvousHandler(self)
 
     @cache_in_self
-    def get_msc4108v2025_rendezvous_handler(self) -> MSC4108v2025RendezvousHandler:
-        return MSC4108v2025RendezvousHandler(self)
+    def get_msc4388_rendezvous_handler(self) -> MSC4388RendezvousHandler:
+        return MSC4388RendezvousHandler(self)
 
     @cache_in_self
     def get_outbound_redis_connection(self) -> "ConnectionHandler":
diff --git a/synapse/synapse_rust/msc4108v2025_rendezvous.pyi b/synapse/synapse_rust/msc4388_rendezvous.pyi
similarity index 86%
rename from synapse/synapse_rust/msc4108v2025_rendezvous.pyi
rename to synapse/synapse_rust/msc4388_rendezvous.pyi
index 514df7818a..a22cf3a017 100644
--- a/synapse/synapse_rust/msc4108v2025_rendezvous.pyi
+++ b/synapse/synapse_rust/msc4388_rendezvous.pyi
@@ -14,15 +14,15 @@ from twisted.web.iweb import IRequest
 
 from synapse.server import HomeServer
 
-class MSC4108v2025RendezvousHandler:
+class MSC4388RendezvousHandler:
     def __init__(
         self,
         homeserver: HomeServer,
         /,
         capacity: int = 100,  # This should be configurable
-        max_content_length: int = 4 * 1024,  # MSC4108 specifies maximum of 4KB
+        max_content_length: int = 4 * 1024,  # MSC4388 specifies maximum of 4KB
         eviction_interval: int = 60 * 1000,
-        ttl: int = 2 * 60 * 1000,  # MSC4108 specifies minimum of 120 seconds
+        ttl: int = 2 * 60 * 1000,  # MSC4388 specifies minimum of 120 seconds
     ) -> None: ...
     def handle_post(self, request: IRequest) -> None: ...
     def handle_get(self, request: IRequest, session_id: str) -> None: ...
diff --git a/tests/rest/client/test_msc4108v2025_rendezvous.py b/tests/rest/client/test_msc4388_rendezvous.py
similarity index 92%
rename from tests/rest/client/test_msc4108v2025_rendezvous.py
rename to tests/rest/client/test_msc4388_rendezvous.py
index 4ea7ab613b..5f996018f7 100644
--- a/tests/rest/client/test_msc4108v2025_rendezvous.py
+++ b/tests/rest/client/test_msc4388_rendezvous.py
@@ -29,12 +29,12 @@ from tests import unittest
 from tests.unittest import checked_cast, override_config
 from tests.utils import HAS_AUTHLIB
 
-msc4108_endpoint = "/_matrix/client/unstable/io.element.msc4108/rendezvous"
+rz_endpoint = "/_matrix/client/unstable/io.element.msc4388/rendezvous"
 
 
 class RendezvousServletTestCase(unittest.HomeserverTestCase):
     """
-    Test the experimental MSC4108 rendezvous endpoint with the latest behaviour.
+    Test the experimental MSC4388 rendezvous endpoint.
     """
 
     servlets = [
@@ -121,18 +121,18 @@ class RendezvousServletTestCase(unittest.HomeserverTestCase):
         return "mock_token_" + username + "_" + device_id
 
     def test_disabled(self) -> None:
-        channel = self.make_request("POST", msc4108_endpoint, {}, access_token=None)
+        channel = self.make_request("POST", rz_endpoint, {}, access_token=None)
         self.assertEqual(channel.code, 404)
 
     @override_config(
         {
             "experimental_features": {
-                "msc4108v2025_mode": "off",
+                "msc4388_mode": "off",
             },
         }
     )
     def test_off(self) -> None:
-        channel = self.make_request("POST", msc4108_endpoint, {}, access_token=None)
+        channel = self.make_request("POST", rz_endpoint, {}, access_token=None)
         self.assertEqual(channel.code, 404)
 
     @unittest.skip_unless(HAS_AUTHLIB, "requires authlib")
@@ -145,7 +145,7 @@ class RendezvousServletTestCase(unittest.HomeserverTestCase):
                 "endpoint": "https://issuer",
             },
             "experimental_features": {
-                "msc4108v2025_mode": "public",
+                "msc4388_mode": "public",
             },
         }
     )
@@ -161,7 +161,7 @@ class RendezvousServletTestCase(unittest.HomeserverTestCase):
         # We can post arbitrary data to the endpoint
         channel = self.make_request(
             "POST",
-            msc4108_endpoint,
+            rz_endpoint,
             {"data": "foo=bar"},
             access_token=None,
         )
@@ -171,7 +171,7 @@ class RendezvousServletTestCase(unittest.HomeserverTestCase):
         expires_ts = channel.json_body["expires_ts"]
         self.assertGreater(expires_ts, self.hs.get_clock().time_msec())
 
-        session_endpoint = msc4108_endpoint + f"/{rendezvous_id}"
+        session_endpoint = rz_endpoint + f"/{rendezvous_id}"
 
         # We can get the data back
         channel = self.make_request(
@@ -207,7 +207,7 @@ class RendezvousServletTestCase(unittest.HomeserverTestCase):
 
         self.assertEqual(channel.code, 409)
         self.assertEqual(
-            channel.json_body["errcode"], "IO_ELEMENT_MSC4108_CONCURRENT_WRITE"
+            channel.json_body["errcode"], "IO_ELEMENT_MSC4388_CONCURRENT_WRITE"
         )
 
         # We should get the updated data
@@ -251,7 +251,7 @@ class RendezvousServletTestCase(unittest.HomeserverTestCase):
                 "endpoint": "https://issuer",
             },
             "experimental_features": {
-                "msc4108v2025_mode": "authenticated",
+                "msc4388_mode": "authenticated",
             },
         }
     )
@@ -270,7 +270,7 @@ class RendezvousServletTestCase(unittest.HomeserverTestCase):
         # This should fail without authentication:
         channel = self.make_request(
             "POST",
-            msc4108_endpoint,
+            rz_endpoint,
             {"data": "foo=bar"},
             access_token=None,
         )
@@ -279,7 +279,7 @@ class RendezvousServletTestCase(unittest.HomeserverTestCase):
         # This should work as we are now authenticated
         channel = self.make_request(
             "POST",
-            msc4108_endpoint,
+            rz_endpoint,
             {"data": "foo=bar"},
             access_token=alice_token,
         )
@@ -289,7 +289,7 @@ class RendezvousServletTestCase(unittest.HomeserverTestCase):
         expires_ts = channel.json_body["expires_ts"]
         self.assertGreater(expires_ts, self.hs.get_clock().time_msec())
 
-        session_endpoint = msc4108_endpoint + f"/{rendezvous_id}"
+        session_endpoint = rz_endpoint + f"/{rendezvous_id}"
 
         # We can get the data back without authentication
         channel = self.make_request(
@@ -355,7 +355,7 @@ class RendezvousServletTestCase(unittest.HomeserverTestCase):
                 "endpoint": "https://issuer",
             },
             "experimental_features": {
-                "msc4108v2025_mode": "public",
+                "msc4388_mode": "public",
             },
         }
     )
@@ -366,12 +366,12 @@ class RendezvousServletTestCase(unittest.HomeserverTestCase):
         # Start a new session
         channel = self.make_request(
             "POST",
-            msc4108_endpoint,
+            rz_endpoint,
             {"data": "foo=bar"},
             access_token=None,
         )
         self.assertEqual(channel.code, 200)
-        session_endpoint = msc4108_endpoint + "/" + channel.json_body["id"]
+        session_endpoint = rz_endpoint + "/" + channel.json_body["id"]
 
         # Sanity check that we can get the data back
         channel = self.make_request(
@@ -403,7 +403,7 @@ class RendezvousServletTestCase(unittest.HomeserverTestCase):
                 "endpoint": "https://issuer",
             },
             "experimental_features": {
-                "msc4108v2025_mode": "public",
+                "msc4388_mode": "public",
             },
         }
     )
@@ -415,12 +415,12 @@ class RendezvousServletTestCase(unittest.HomeserverTestCase):
         # Start a new session
         channel = self.make_request(
             "POST",
-            msc4108_endpoint,
+            rz_endpoint,
             {"data": "foo=bar"},
             access_token=None,
         )
         self.assertEqual(channel.code, 200)
-        session_endpoint = msc4108_endpoint + "/" + channel.json_body["id"]
+        session_endpoint = rz_endpoint + "/" + channel.json_body["id"]
 
         # Sanity check that we can get the data back
         channel = self.make_request(
@@ -438,7 +438,7 @@ class RendezvousServletTestCase(unittest.HomeserverTestCase):
         for _ in range(100):
             channel = self.make_request(
                 "POST",
-                msc4108_endpoint,
+                rz_endpoint,
                 {"data": "foo=bar"},
                 access_token=None,
             )
@@ -475,7 +475,7 @@ class RendezvousServletTestCase(unittest.HomeserverTestCase):
                 "endpoint": "https://issuer",
             },
             "experimental_features": {
-                "msc4108v2025_mode": "public",
+                "msc4388_mode": "public",
             },
         }
     )
@@ -487,12 +487,12 @@ class RendezvousServletTestCase(unittest.HomeserverTestCase):
         # Start a new session
         channel = self.make_request(
             "POST",
-            msc4108_endpoint,
+            rz_endpoint,
             {"data": "foo=bar"},
             access_token=None,
         )
         self.assertEqual(channel.code, 200)
-        session_endpoint = msc4108_endpoint + "/" + channel.json_body["id"]
+        session_endpoint = rz_endpoint + "/" + channel.json_body["id"]
         # We advance the clock to make sure that this entry is the "lowest" in the session list
         self.reactor.advance(1)
 
@@ -509,7 +509,7 @@ class RendezvousServletTestCase(unittest.HomeserverTestCase):
         for _ in range(200):
             channel = self.make_request(
                 "POST",
-                msc4108_endpoint,
+                rz_endpoint,
                 {"data": "foo=bar"},
                 access_token=None,
             )
@@ -534,7 +534,7 @@ class RendezvousServletTestCase(unittest.HomeserverTestCase):
                 "endpoint": "https://issuer",
             },
             "experimental_features": {
-                "msc4108v2025_mode": "public",
+                "msc4388_mode": "public",
             },
         }
     )
@@ -548,7 +548,7 @@ class RendezvousServletTestCase(unittest.HomeserverTestCase):
         for invalid_data in invalid_datas:
             channel = self.make_request(
                 "POST",
-                msc4108_endpoint,
+                rz_endpoint,
                 {"data": invalid_data},
                 access_token=None,
             )
@@ -558,7 +558,7 @@ class RendezvousServletTestCase(unittest.HomeserverTestCase):
         # Make a valid request
         channel = self.make_request(
             "POST",
-            msc4108_endpoint,
+            rz_endpoint,
             {"data": "test"},
             access_token=None,
         )
@@ -566,7 +566,7 @@ class RendezvousServletTestCase(unittest.HomeserverTestCase):
         rendezvous_id = channel.json_body["id"]
         sequence_token = channel.json_body["sequence_token"]
 
-        session_endpoint = msc4108_endpoint + f"/{rendezvous_id}"
+        session_endpoint = rz_endpoint + f"/{rendezvous_id}"
 
         # We can't update the data with invalid data
         for invalid_data in invalid_datas:
@@ -589,7 +589,7 @@ class RendezvousServletTestCase(unittest.HomeserverTestCase):
                 "endpoint": "https://issuer",
             },
             "experimental_features": {
-                "msc4108v2025_mode": "public",
+                "msc4388_mode": "public",
             },
         }
     )
@@ -601,7 +601,7 @@ class RendezvousServletTestCase(unittest.HomeserverTestCase):
 
         channel = self.make_request(
             "POST",
-            msc4108_endpoint,
+            rz_endpoint,
             {"data": too_long_data},
             access_token=None,
         )
@@ -611,7 +611,7 @@ class RendezvousServletTestCase(unittest.HomeserverTestCase):
         # Make a valid request
         channel = self.make_request(
             "POST",
-            msc4108_endpoint,
+            rz_endpoint,
             {"data": "test"},
             access_token=None,
         )
@@ -619,7 +619,7 @@ class RendezvousServletTestCase(unittest.HomeserverTestCase):
         rendezvous_id = channel.json_body["id"]
         sequence_token = channel.json_body["sequence_token"]
 
-        session_endpoint = msc4108_endpoint + f"/{rendezvous_id}"
+        session_endpoint = rz_endpoint + f"/{rendezvous_id}"
 
         # We can't update the data with invalid data
         channel = self.make_request(