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The following commit(s) were added to refs/heads/camel-4.18.x by this push:
new f184cd8c4825 CAMEL-23588: camel-undertow - extend
UndertowHeaderFilterStrategy to filter the legacy websocket.* exchange-header
prefix (#23992)
f184cd8c4825 is described below
commit f184cd8c4825f891d211307ce7ad122a3920514e
Author: Andrea Cosentino <[email protected]>
AuthorDate: Fri Jun 12 18:33:25 2026 +0200
CAMEL-23588: camel-undertow - extend UndertowHeaderFilterStrategy to filter
the legacy websocket.* exchange-header prefix (#23992)
Backport to camel-4.18.x of the main-branch change (d5a717dd0f8). Adds the
legacy websocket.* prefix to the undertow HeaderFilterStrategy in/out
filters
(in addition to Camel* / camel* / org.apache.camel.*) and documents it in
the
4.18 upgrade guide, alongside the CAMEL-23532 vertx-websocket /
atmosphere-websocket
/ iggy family.
---
.../undertow/UndertowHeaderFilterStrategy.java | 19 +++++++++
.../ROOT/pages/camel-4x-upgrade-guide-4_18.adoc | 47 ++++++++++++++++++++++
2 files changed, 66 insertions(+)
diff --git
a/components/camel-undertow/src/main/java/org/apache/camel/component/undertow/UndertowHeaderFilterStrategy.java
b/components/camel-undertow/src/main/java/org/apache/camel/component/undertow/UndertowHeaderFilterStrategy.java
index 23c0d894d7d7..2d92318ed5be 100644
---
a/components/camel-undertow/src/main/java/org/apache/camel/component/undertow/UndertowHeaderFilterStrategy.java
+++
b/components/camel-undertow/src/main/java/org/apache/camel/component/undertow/UndertowHeaderFilterStrategy.java
@@ -21,10 +21,29 @@ import org.apache.camel.http.base.HttpHeaderFilterStrategy;
public class UndertowHeaderFilterStrategy extends HttpHeaderFilterStrategy {
+ /**
+ * Legacy {@code websocket.*} Exchange-header prefix used by {@code
UndertowConstants} for the dispatch and event
+ * headers ({@code websocket.connectionKey}, {@code
websocket.connectionKey.list}, {@code websocket.sendToAll},
+ * {@code websocket.eventType}, {@code websocket.eventTypeEnum}, {@code
websocket.channel},
+ * {@code websocket.exchange}). Added to the in/out filter prefixes
(CAMEL-23588) so the undertow boundary does not
+ * propagate these values onto outbound wire frames or map them in from
inbound HTTP-style headers. This is
+ * defence-in-depth — cross-component routes that flow an untrusted
message into an undertow producer should also
+ * {@code .removeHeaders("websocket.*")} at the trust boundary, because
the producer reads these headers via
+ * {@code in.getHeader(...)} which bypasses the {@code
HeaderFilterStrategy}.
+ */
+ static final String WEBSOCKET_FILTER_STARTS_WITH = "websocket.";
+
public UndertowHeaderFilterStrategy() {
initialize();
}
+ @Override
+ protected void initialize() {
+ super.initialize();
+ setOutFilterStartsWith("Camel", "camel", WEBSOCKET_FILTER_STARTS_WITH);
+ setInFilterStartsWith("Camel", "camel", WEBSOCKET_FILTER_STARTS_WITH);
+ }
+
@Override
public boolean applyFilterToExternalHeaders(String headerName, Object
headerValue, Exchange exchange) {
boolean skip = io.undertow.util.HttpString.tryFromString(headerName)
== null;
diff --git
a/docs/user-manual/modules/ROOT/pages/camel-4x-upgrade-guide-4_18.adoc
b/docs/user-manual/modules/ROOT/pages/camel-4x-upgrade-guide-4_18.adoc
index 1d040ae9e08b..a63bb754b8bc 100644
--- a/docs/user-manual/modules/ROOT/pages/camel-4x-upgrade-guide-4_18.adoc
+++ b/docs/user-manual/modules/ROOT/pages/camel-4x-upgrade-guide-4_18.adoc
@@ -1203,6 +1203,53 @@ directions, aligning the component with the rest of the
Camel component catalog.
`Camel`-prefixed user-header names from Iggy messages can supply a custom
`headerFilterStrategy`
to restore the previous behaviour.
+=== camel-undertow - potential breaking change
+
+`UndertowHeaderFilterStrategy` now also filters the legacy `websocket.*`
+Exchange-header prefix (in addition to the `Camel*` / `camel*` /
+`org.apache.camel.*` prefixes it already filtered). This applies to both the
+in (wire -> exchange) and out (exchange -> wire) directions and follows the
+dedicated-filter-strategy shape used by CAMEL-23532 for
+`camel-vertx-websocket` / `camel-atmosphere-websocket` / `camel-iggy`.
+
+The constants in `UndertowConstants` (`CONNECTION_KEY`, `CONNECTION_KEY_LIST`,
+`SEND_TO_ALL`, `EVENT_TYPE`, `EVENT_TYPE_ENUM`, `CHANNEL`, `EXCHANGE`) keep
+their existing string values (`websocket.connectionKey`,
+`websocket.connectionKey.list`, `websocket.sendToAll`, etc.) because they are
+part of the undertow component's externally-visible API contract; routes
+referencing them (symbolically or by literal value) continue to work
+unchanged within an undertow route.
+
+The behaviour change applies at undertow's transport boundary:
+
+* Outbound (exchange -> wire): if an exchange ends up at an undertow producer
+ carrying an Exchange header whose name starts with `websocket.`, that
+ header will no longer be propagated onto the outbound HTTP/websocket
+ request as a wire-level header.
+* Inbound (wire -> exchange): if an undertow consumer receives a request
+ whose wire-level headers include a name starting with `websocket.`, that
+ header will no longer be mapped into the resulting Camel exchange.
+
+Note that the `HeaderFilterStrategy` only governs the transport boundary; it
+does not prevent cross-component header injection (for example, an
+`http -> undertow` route where the HTTP consumer maps an attacker-supplied
+`websocket.connectionKey` header into the exchange and the undertow producer
+then reads it via `in.getHeader(...)` to dispatch to a specific peer). For
+defence in depth at the trust boundary, route authors should explicitly strip
+these headers from untrusted inbound traffic, for example:
+
+[source,java]
+----
+from("jetty:http://0.0.0.0:8080/api";)
+ .removeHeaders("websocket.*")
+ .to("undertow:ws://internal-broker/notifications");
+----
+
+Routes that intentionally relied on undertow mapping `websocket.*` wire
+headers in or out can supply a custom `headerFilterStrategy` endpoint option
+to restore the previous behaviour.
+
+
=== camel-aws2-sqs
`Sqs2HeaderFilterStrategy` now also configures an inbound filter aligned with
the existing
