diff --git a/.palantir/revapi.yml b/.palantir/revapi.yml
new file mode 100644
index 000000000..7909ec590
--- /dev/null
+++ b/.palantir/revapi.yml
@@ -0,0 +1,6 @@
+acceptedBreaks:
+  "8.68.0":
+    com.palantir.conjure.java:conjure-undertow-lib:
+    - code: "java.method.addedToInterface"
+      new: "method <T> java.util.Optional<T> com.palantir.conjure.java.undertow.lib.RequestContext::attachment(io.undertow.util.AttachmentKey<T>)"
+      justification: "Add attachment() method to RequestContext, following the pattern of cookie(). RequestContext is only implemented by conjure-java-undertow-runtime."
diff --git a/conjure-java-undertow-runtime/src/main/java/com/palantir/conjure/java/undertow/runtime/ConjureContexts.java b/conjure-java-undertow-runtime/src/main/java/com/palantir/conjure/java/undertow/runtime/ConjureContexts.java
index 9b2c40d95..1809331f6 100644
--- a/conjure-java-undertow-runtime/src/main/java/com/palantir/conjure/java/undertow/runtime/ConjureContexts.java
+++ b/conjure-java-undertow-runtime/src/main/java/com/palantir/conjure/java/undertow/runtime/ConjureContexts.java
@@ -28,6 +28,7 @@
 import com.palantir.logsafe.logger.SafeLoggerFactory;
 import io.undertow.server.HttpServerExchange;
 import io.undertow.server.handlers.Cookie;
+import io.undertow.util.AttachmentKey;
 import io.undertow.util.HeaderValues;
 import java.security.cert.Certificate;
 import java.util.Collections;
@@ -81,6 +82,11 @@ public Optional<String> firstHeader(String headerName) {
             return Optional.ofNullable(exchange.getRequestHeaders().getFirst(headerName));
         }
 
+        @Override
+        public <T> Optional<T> attachment(AttachmentKey<T> attachmentKey) {
+            return Optional.ofNullable(exchange.getAttachment(attachmentKey));
+        }
+
         @Override
         public Optional<String> cookie(String cookieName) {
             Cookie cookie;
diff --git a/conjure-undertow-lib/src/main/java/com/palantir/conjure/java/undertow/lib/RequestContext.java b/conjure-undertow-lib/src/main/java/com/palantir/conjure/java/undertow/lib/RequestContext.java
index dce10b758..e1c4e5025 100644
--- a/conjure-undertow-lib/src/main/java/com/palantir/conjure/java/undertow/lib/RequestContext.java
+++ b/conjure-undertow-lib/src/main/java/com/palantir/conjure/java/undertow/lib/RequestContext.java
@@ -20,6 +20,7 @@
 import com.google.common.collect.ListMultimap;
 import com.palantir.logsafe.Arg;
 import com.palantir.logsafe.Unsafe;
+import io.undertow.util.AttachmentKey;
 import java.security.cert.Certificate;
 import java.util.List;
 import java.util.Optional;
@@ -50,6 +51,12 @@ public interface RequestContext {
      */
     Optional<String> firstHeader(String headerName);
 
+    /**
+     * Returns the attachment associated with the given {@code key}.
+     * An {@link Optional#empty()} is returned if no such attachment exists.
+     */
+    <T> Optional<T> attachment(AttachmentKey<T> key);
+
     /**
      * Returns the value of the cookie named {@code cookieName}.
      * An {@link Optional#empty()} is returned if no such cookie exists.