diff --git a/spring-web-reactive/src/main/java/org/springframework/web/server/session/CookieWebSessionIdResolver.java b/spring-web-reactive/src/main/java/org/springframework/web/server/session/CookieWebSessionIdResolver.java
index 51aeaae895b..8530117ccc4 100644
--- a/spring-web-reactive/src/main/java/org/springframework/web/server/session/CookieWebSessionIdResolver.java
+++ b/spring-web-reactive/src/main/java/org/springframework/web/server/session/CookieWebSessionIdResolver.java
@@ -18,13 +18,11 @@ package org.springframework.web.server.session;
 import java.time.Duration;
 import java.util.Collections;
 import java.util.List;
-import java.util.Map;
-import java.util.Optional;
+import java.util.stream.Collectors;
 
 import org.springframework.http.HttpCookie;
 import org.springframework.http.ServerHttpCookie;
 import org.springframework.util.Assert;
-import org.springframework.util.CollectionUtils;
 import org.springframework.util.MultiValueMap;
 import org.springframework.util.StringUtils;
 import org.springframework.web.server.ServerWebExchange;
@@ -77,10 +75,13 @@ public class CookieWebSessionIdResolver implements WebSessionIdResolver {
 
 
 	@Override
-	public Optional<String> resolveSessionId(ServerWebExchange exchange) {
+	public List<String> resolveSessionId(ServerWebExchange exchange) {
 		MultiValueMap<String, HttpCookie> cookieMap = exchange.getRequest().getCookies();
-		HttpCookie cookie = cookieMap.getFirst(getCookieName());
-		return (cookie != null ? Optional.of(cookie.getValue()) : Optional.empty());
+		List<HttpCookie> cookies = cookieMap.get(getCookieName());
+		if (cookies == null) {
+			return Collections.emptyList();
+		}
+		return cookies.stream().map(HttpCookie::getValue).collect(Collectors.toList());
 	}
 
 	@Override
diff --git a/spring-web-reactive/src/main/java/org/springframework/web/server/session/DefaultWebSessionManager.java b/spring-web-reactive/src/main/java/org/springframework/web/server/session/DefaultWebSessionManager.java
index 8c1756c313e..5bcb233b958 100644
--- a/spring-web-reactive/src/main/java/org/springframework/web/server/session/DefaultWebSessionManager.java
+++ b/spring-web-reactive/src/main/java/org/springframework/web/server/session/DefaultWebSessionManager.java
@@ -17,9 +17,10 @@ package org.springframework.web.server.session;
 
 import java.time.Clock;
 import java.time.Instant;
-import java.util.Optional;
+import java.util.List;
 import java.util.UUID;
 
+import reactor.core.publisher.Flux;
 import reactor.core.publisher.Mono;
 
 import org.springframework.util.Assert;
@@ -98,9 +99,8 @@ public class DefaultWebSessionManager implements WebSessionManager {
 
 	@Override
 	public Mono<WebSession> getSession(ServerWebExchange exchange) {
-		return Mono.fromCallable(() -> getSessionIdResolver().resolveSessionId(exchange))
-				.where(Optional::isPresent)
-				.map(Optional::get)
+		return Flux.fromIterable(getSessionIdResolver().resolveSessionId(exchange))
+				.next()
 				.then(this.sessionStore::retrieveSession)
 				.then(session -> validateSession(exchange, session))
 				.otherwiseIfEmpty(createSession(exchange))
@@ -147,8 +147,8 @@ public class DefaultWebSessionManager implements WebSessionManager {
 		// Force explicit start
 		session.start();
 
-		Optional<String> requestedId = getSessionIdResolver().resolveSessionId(exchange);
-		if (!requestedId.isPresent() || !session.getId().equals(requestedId.get())) {
+		List<String> requestedIds = getSessionIdResolver().resolveSessionId(exchange);
+		if (requestedIds.isEmpty() || !session.getId().equals(requestedIds.get(0))) {
 			this.sessionIdResolver.setSessionId(exchange, session.getId());
 		}
 		return this.sessionStore.storeSession(session);
diff --git a/spring-web-reactive/src/main/java/org/springframework/web/server/session/WebSessionIdResolver.java b/spring-web-reactive/src/main/java/org/springframework/web/server/session/WebSessionIdResolver.java
index 151952716b0..a57a1cfa7ec 100644
--- a/spring-web-reactive/src/main/java/org/springframework/web/server/session/WebSessionIdResolver.java
+++ b/spring-web-reactive/src/main/java/org/springframework/web/server/session/WebSessionIdResolver.java
@@ -15,7 +15,7 @@
  */
 package org.springframework.web.server.session;
 
-import java.util.Optional;
+import java.util.List;
 
 import org.springframework.web.server.ServerWebExchange;
 
@@ -31,11 +31,11 @@ import org.springframework.web.server.ServerWebExchange;
 public interface WebSessionIdResolver {
 
 	/**
-	 * Resolve the session id associated with the request.
+	 * Resolve the session id's associated with the request.
 	 * @param exchange the current exchange
-	 * @return the session id if present
+	 * @return the session id's or an empty list
 	 */
-	Optional<String> resolveSessionId(ServerWebExchange exchange);
+	List<String> resolveSessionId(ServerWebExchange exchange);
 
 	/**
 	 * Send the given session id to the client or if the session id is "null"
diff --git a/spring-web-reactive/src/test/java/org/springframework/web/server/session/DefaultWebSessionManagerTests.java b/spring-web-reactive/src/test/java/org/springframework/web/server/session/DefaultWebSessionManagerTests.java
index 5342f97f1a7..c7c17b8a6ae 100644
--- a/spring-web-reactive/src/test/java/org/springframework/web/server/session/DefaultWebSessionManagerTests.java
+++ b/spring-web-reactive/src/test/java/org/springframework/web/server/session/DefaultWebSessionManagerTests.java
@@ -19,7 +19,9 @@ import java.net.URI;
 import java.time.Clock;
 import java.time.Duration;
 import java.time.Instant;
-import java.util.Optional;
+import java.util.ArrayList;
+import java.util.Collections;
+import java.util.List;
 
 import org.junit.Before;
 import org.junit.Test;
@@ -27,9 +29,9 @@ import org.junit.Test;
 import org.springframework.http.HttpMethod;
 import org.springframework.http.server.reactive.MockServerHttpRequest;
 import org.springframework.http.server.reactive.MockServerHttpResponse;
-import org.springframework.web.server.adapter.DefaultServerWebExchange;
 import org.springframework.web.server.ServerWebExchange;
 import org.springframework.web.server.WebSession;
+import org.springframework.web.server.adapter.DefaultServerWebExchange;
 
 import static org.junit.Assert.assertEquals;
 import static org.junit.Assert.assertFalse;
@@ -64,7 +66,7 @@ public class DefaultWebSessionManagerTests {
 
 	@Test
 	public void getSessionPassive() throws Exception {
-		this.idResolver.setIdToResolve(Optional.empty());
+		this.idResolver.setIdsToResolve(Collections.emptyList());
 		WebSession session = this.manager.getSession(this.exchange).get();
 
 		assertNotNull(session);
@@ -79,7 +81,7 @@ public class DefaultWebSessionManagerTests {
 
 	@Test
 	public void getSessionForceCreate() throws Exception {
-		this.idResolver.setIdToResolve(Optional.empty());
+		this.idResolver.setIdsToResolve(Collections.emptyList());
 		WebSession session = this.manager.getSession(this.exchange).get();
 		session.start();
 		session.save();
@@ -92,7 +94,7 @@ public class DefaultWebSessionManagerTests {
 
 	@Test
 	public void getSessionAddAttribute() throws Exception {
-		this.idResolver.setIdToResolve(Optional.empty());
+		this.idResolver.setIdsToResolve(Collections.emptyList());
 		WebSession session = this.manager.getSession(this.exchange).get();
 		session.getAttributes().put("foo", "bar");
 		session.save();
@@ -105,7 +107,7 @@ public class DefaultWebSessionManagerTests {
 		DefaultWebSession existing = new DefaultWebSession("1", Clock.systemDefaultZone());
 		this.manager.getSessionStore().storeSession(existing);
 
-		this.idResolver.setIdToResolve(Optional.of("1"));
+		this.idResolver.setIdsToResolve(Collections.singletonList("1"));
 		WebSession actual = this.manager.getSession(this.exchange).get();
 		assertSame(existing, actual);
 	}
@@ -118,7 +120,7 @@ public class DefaultWebSessionManagerTests {
 		existing.setLastAccessTime(Instant.now(clock).minus(Duration.ofMinutes(31)));
 		this.manager.getSessionStore().storeSession(existing);
 
-		this.idResolver.setIdToResolve(Optional.of("1"));
+		this.idResolver.setIdsToResolve(Collections.singletonList("1"));
 		WebSession actual = this.manager.getSession(this.exchange).get();
 		assertNotSame(existing, actual);
 	}
@@ -126,13 +128,13 @@ public class DefaultWebSessionManagerTests {
 
 	private static class TestWebSessionIdResolver implements WebSessionIdResolver {
 
-		private Optional<String> idToResolve = Optional.empty();
+		private List<String> idsToResolve = new ArrayList<>();
 
 		private String id = null;
 
 
-		public void setIdToResolve(Optional<String> idToResolve) {
-			this.idToResolve = idToResolve;
+		public void setIdsToResolve(List<String> idsToResolve) {
+			this.idsToResolve = idsToResolve;
 		}
 
 		public String getId() {
@@ -140,8 +142,8 @@ public class DefaultWebSessionManagerTests {
 		}
 
 		@Override
-		public Optional<String> resolveSessionId(ServerWebExchange exchange) {
-			return this.idToResolve;
+		public List<String> resolveSessionId(ServerWebExchange exchange) {
+			return this.idsToResolve;
 		}
 
 		@Override