diff --git a/CHANGELOG.md b/CHANGELOG.md
index a815c8469..321dba96d 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,3 +1,8 @@
+Changes in [34.3.1](https://github.com/matrix-org/matrix-js-sdk/releases/tag/v34.3.1) (2024-08-20)
+==================================================================================================
+# Security
+- Fixes for [CVE-2024-42369](https://nvd.nist.gov/vuln/detail/CVE-2024-42369) / [GHSA-vhr5-g3pm-49fm](https://github.com/matrix-org/matrix-js-sdk/security/advisories/GHSA-vhr5-g3pm-49fm).
+
 Changes in [34.3.0](https://github.com/matrix-org/matrix-js-sdk/releases/tag/v34.3.0) (2024-08-13)
 ==================================================================================================
 ## ✨ Features
diff --git a/package.json b/package.json
index 49dea49bd..075d821ec 100644
--- a/package.json
+++ b/package.json
@@ -1,6 +1,6 @@
 {
     "name": "matrix-js-sdk",
-    "version": "34.3.0",
+    "version": "34.3.1",
     "description": "Matrix Client-Server SDK for Javascript",
     "engines": {
         "node": ">=20.0.0"
diff --git a/src/client.ts b/src/client.ts
index de0af218f..9da03de8e 100644
--- a/src/client.ts
+++ b/src/client.ts
@@ -5587,10 +5587,15 @@ export class MatrixClient extends TypedEventEmitter<EmittedEvents, ClientEventHa
 
     private findPredecessorRooms(room: Room, verifyLinks: boolean, msc3946ProcessDynamicPredecessor: boolean): Room[] {
         const ret: Room[] = [];
+        const seenRoomIDs = new Set<string>([room.roomId]);
 
         // Work backwards from newer to older rooms
         let predecessorRoomId = room.findPredecessor(msc3946ProcessDynamicPredecessor)?.roomId;
         while (predecessorRoomId !== null) {
+            if (predecessorRoomId) {
+                if (seenRoomIDs.has(predecessorRoomId)) break;
+                seenRoomIDs.add(predecessorRoomId);
+            }
             const predecessorRoom = this.getRoom(predecessorRoomId);
             if (predecessorRoom === null) {
                 break;