diff --git a/com.unity.render-pipelines.high-definition/CHANGELOG.md b/com.unity.render-pipelines.high-definition/CHANGELOG.md
index 6e7a1f0188c..4cfad028fc0 100644
--- a/com.unity.render-pipelines.high-definition/CHANGELOG.md
+++ b/com.unity.render-pipelines.high-definition/CHANGELOG.md
@@ -51,6 +51,7 @@ and this project adheres to [Semantic Versioning](http://semver.org/spec/v2.0.0.
 - Fixed texture fields for volume parameters accepting textures with wrong dimensions.
 - Fixed Realtime lightmap not working correctly in player with various lit shader (case 1360021)
 - Fixed unexpectedly strong contribution from directional lights in path-traced volumetric scattering (case 1304688).
+- Fixed memory leak with XR combined occlusion meshes (case 1366173).
 
 ### Changed
 - Visual Environment ambient mode is now Dynamic by default.
diff --git a/com.unity.render-pipelines.high-definition/Runtime/RenderPipeline/XR/XRSystem.cs b/com.unity.render-pipelines.high-definition/Runtime/RenderPipeline/XR/XRSystem.cs
index b7978e1aa20..4c2dd0ba8a6 100644
--- a/com.unity.render-pipelines.high-definition/Runtime/RenderPipeline/XR/XRSystem.cs
+++ b/com.unity.render-pipelines.high-definition/Runtime/RenderPipeline/XR/XRSystem.cs
@@ -167,8 +167,11 @@ internal int GetMaxViews()
 
         internal void ReleaseFrame()
         {
-            foreach ((Camera _, XRPass xrPass) in framePasses)
+            for (int i = 0; i < framePasses.Count; i++)
             {
+                // Pop from the back to keep initial ordering (see implementation of ObjectPool)
+                (Camera _, XRPass xrPass) = framePasses[framePasses.Count - i - 1];
+
                 if (xrPass != emptyPass)
                     XRPass.Release(xrPass);
             }
diff --git a/com.unity.render-pipelines.universal/CHANGELOG.md b/com.unity.render-pipelines.universal/CHANGELOG.md
index 2504beb95eb..9c75d0470b4 100644
--- a/com.unity.render-pipelines.universal/CHANGELOG.md
+++ b/com.unity.render-pipelines.universal/CHANGELOG.md
@@ -20,6 +20,7 @@ and this project adheres to [Semantic Versioning](http://semver.org/spec/v2.0.0.
 - URP asset can now use multi-edit. [case 1364966](https://issuetracker.unity3d.com/issues/urp-universalrenderpipelineasset-does-not-support-multi-edit)
 - Fixed an issue in where the current open scene didn't load after running the converters. [case 1365101]
 - Added "Conservative Enclosing Sphere" setting to fix shadow frustum culling issue where shadows are erroneously culled in corners of cascades [case 1153151](https://issuetracker.unity3d.com/issues/lwrp-shadows-are-being-culled-incorrectly-in-the-corner-of-the-camera-viewport-when-the-far-clip-plane-is-small)
+- Fixed memory leak with XR combined occlusion meshes. [case 1366173]
 
 ## [12.0.0] - 2021-01-11
 ### Added
diff --git a/com.unity.render-pipelines.universal/Runtime/XR/XRSystem.cs b/com.unity.render-pipelines.universal/Runtime/XR/XRSystem.cs
index 8b566bc918b..ee5a4e69076 100644
--- a/com.unity.render-pipelines.universal/Runtime/XR/XRSystem.cs
+++ b/com.unity.render-pipelines.universal/Runtime/XR/XRSystem.cs
@@ -201,8 +201,11 @@ internal List<XRPass> SetupFrame(Camera camera, bool enableXRRendering)
 
         internal void ReleaseFrame()
         {
-            foreach (XRPass xrPass in framePasses)
+            for (int i = 0; i < framePasses.Count; i++)
             {
+                // Pop from the back to keep initial ordering (see implementation of ObjectPool)
+                var xrPass = framePasses[framePasses.Count - i - 1];
+
                 if (xrPass != emptyPass)
                     XRPass.Release(xrPass);
             }