diff --git a/libervia/backend/core/core_types.py b/libervia/backend/core/core_types.py
index 7d6c147a..ca9cc3a7 100644
--- a/libervia/backend/core/core_types.py
+++ b/libervia/backend/core/core_types.py
@@ -101,6 +101,10 @@ class SatXMPPEntity(ABC):
     discoHandler: disco.DiscoHandler
     messageProt: "SatMessageProtocol"
     identities: list[disco.DiscoIdentity]
+    # Map from (from_jid, message_id) to internal uid.
+    # This is updated when message are received during message parsing, and this is
+    # available only for message received during this session.
+    mess_id2uid: dict[tuple[str, str], str]
     # Fire when entity is connected
     conn_deferred: defer.Deferred
     xmlstream: mod_xmlstream.XmlStream
diff --git a/libervia/backend/plugins/plugin_xep_0367.py b/libervia/backend/plugins/plugin_xep_0367.py
new file mode 100644
index 00000000..da1ebc1e
--- /dev/null
+++ b/libervia/backend/plugins/plugin_xep_0367.py
@@ -0,0 +1,142 @@
+#!/usr/bin/env python3
+
+# Copyright (C) 2009-2026 Jérôme Poisson (goffi@goffi.org)
+
+# This program is free software: you can redistribute it and/or modify
+# it under the terms of the GNU Affero General Public License as published by
+# the Free Software Foundation, either version 3 of the License, or
+# (at your option) any later version.
+
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU Affero General Public License for more details.
+
+# You should have received a copy of the GNU Affero General Public License
+# along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+from typing import Any, Final, Self
+
+from pydantic import BaseModel, Field
+from twisted.words.protocols.jabber import xmlstream
+from twisted.words.xish import domish
+from tx_xmpp import disco, itx_xmpp
+from zope.interface import implementer
+
+from libervia.backend.core import exceptions
+from libervia.backend.core.constants import Const as C
+from libervia.backend.core.core_types import SatXMPPEntity
+from libervia.backend.core.i18n import _
+from libervia.backend.core.log import getLogger
+
+log = getLogger(__name__)
+
+EXTRA_KEY: Final = "attached_to"
+
+NS_MESSAGE_ATTACHING = "urn:xmpp:message-attaching:1"
+
+
+PLUGIN_INFO = {
+    C.PI_NAME: "Message Attaching",
+    C.PI_IMPORT_NAME: "XEP-0367",
+    C.PI_TYPE: "XEP",
+    C.PI_MODES: C.PLUG_MODE_BOTH,
+    C.PI_PROTOCOLS: ["XEP-0367"],
+    C.PI_MAIN: "XEP_0367",
+    C.PI_HANDLER: "yes",
+    C.PI_DESCRIPTION: _("""Implementation of XEP-0367 (Message Attaching)"""),
+}
+
+
+class AttachedTo(BaseModel):
+    """Attach-to resolution data."""
+
+    uid: str | None = Field(
+        default=None,
+        description="Libervia internal UID of the message to attach to, if resolved.",
+    )
+    stanza_id: str | None = Field(
+        description="XMPP stanza id from <attach-to/>.",
+    )
+
+    def to_element(self) -> domish.Element:
+        """Build the <attach-to/> element from this instance's data.
+
+        @return: <attach-to/> element.
+        @raise exceptions.DataError: If stanza_id is missing.
+        """
+        if self.stanza_id is None:
+            raise exceptions.DataError("stanza_id is missing")
+        return domish.Element(
+            (NS_MESSAGE_ATTACHING, "attach-to"),
+            attribs={"id": self.uid or self.stanza_id},
+        )
+
+    @classmethod
+    def from_element(cls, element: domish.Element) -> Self:
+        """Create an AttachedTo instance from an <attach-to/> element.
+
+        @param element: <attach-to/> element.
+        @return: AttachedTo instance with raw_value set, uid to be resolved later.
+        """
+        return cls(stanza_id=str(element["id"]))
+
+
+class XEP_0367:
+
+    def __init__(self, host) -> None:
+        log.info(f"Plugin {PLUGIN_INFO[C.PI_NAME]!r} initialization.")
+        self.host = host
+        host.register_namespace("message-attaching", NS_MESSAGE_ATTACHING)
+        # priority=10 so "attached_to" is parsed before plugins which need it (e.g.
+        # XEP-0447)
+        host.trigger.add("message_parse", self._message_parse_trigger, priority=10)
+
+    async def _message_parse_trigger(
+        self,
+        client: SatXMPPEntity,
+        message_elt: domish.Element,
+        data: dict[str, Any],
+    ) -> bool:
+        """Parse <attach-to/> element and resolve UID.
+
+        @param client: Client instance.
+        @param message_elt: The <message/> element.
+        @param data: Parsed message data.
+        @return: True to continue message processing.
+        """
+        attach_to_elt = next(
+            message_elt.elements(NS_MESSAGE_ATTACHING, "attach-to"), None
+        )
+        if attach_to_elt is not None:
+            attached_to = AttachedTo.from_element(attach_to_elt)
+            from_jid = data["from"]
+            uid = (
+                client.mess_id2uid.get((from_jid, attached_to.stanza_id))
+                if attached_to.stanza_id is not None
+                else None
+            )
+            if uid is None:
+                log.warning(
+                    f"No matching UID found for attach-to id {attached_to.stanza_id!r} "
+                    f"from {from_jid!r}"
+                )
+            else:
+                attached_to.uid = uid
+            data["extra"][EXTRA_KEY] = attached_to.model_dump()
+        return True
+
+    def get_handler(self, client: SatXMPPEntity) -> "XEP0367Handler":
+        return XEP0367Handler()
+
+
+@implementer(itx_xmpp.IDisco)
+class XEP0367Handler(xmlstream.XMPPHandler):
+
+    def getDiscoInfo(self, requestor: str, target: str, nodeIdentifier: str = "") -> list:
+        return [disco.DiscoFeature(NS_MESSAGE_ATTACHING)]
+
+    def getDiscoItems(
+        self, requestor: str, target: str, nodeIdentifier: str = ""
+    ) -> list:
+        return []