diff --git a/ci/matrix-synapse/fixtures.yaml b/ci/matrix-synapse/fixtures.yaml
index fb5d192..a6ef53c 100644
--- a/ci/matrix-synapse/fixtures.yaml
+++ b/ci/matrix-synapse/fixtures.yaml
@@ -40,7 +40,7 @@ spec:
       containers:
         - name: generate
           # Same image the chart deploys (appVersion of matrix-synapse).
-          image: ghcr.io/element-hq/synapse:v1.149.1
+          image: ghcr.io/element-hq/synapse:v1.159.0
           args: ["generate"]
           env:
             - name: SYNAPSE_SERVER_NAME
diff --git a/ci/matrix-synapse/test-values.yaml b/ci/matrix-synapse/test-values.yaml
index 622c13b..1657582 100644
--- a/ci/matrix-synapse/test-values.yaml
+++ b/ci/matrix-synapse/test-values.yaml
@@ -1,6 +1,8 @@
+secrets:
+  configSecretRef: op://ci/matrix-synapse-config
+
 matrix:
   serverName: synapse.ci.local
-  configSecretRef: op://ci/matrix-synapse-config
   delegation:
     enabled: true
     serverUrl: ci.local
diff --git a/matrix-synapse/Chart.yaml b/matrix-synapse/Chart.yaml
index c5e6b12..7af98eb 100644
--- a/matrix-synapse/Chart.yaml
+++ b/matrix-synapse/Chart.yaml
@@ -3,7 +3,7 @@ name: matrix-synapse
 description: A Helm chart to deploy a Matrix Synapse server on Kubernetes
 icon: https://raw.githubusercontent.com/element-hq/synapse/develop/docs/favicon.png
 type: application
-version: 4.2.1+upv1.159.0
+version: 5.0.0+upv1.159.0
 appVersion: "v1.159.0"
 maintainers:
   - name: jklein
\ No newline at end of file
diff --git a/matrix-synapse/templates/matrix-delegation-nginx.configmap.yaml b/matrix-synapse/templates/matrix-delegation-nginx.configmap.yaml
index ddafd98..1e86398 100644
--- a/matrix-synapse/templates/matrix-delegation-nginx.configmap.yaml
+++ b/matrix-synapse/templates/matrix-delegation-nginx.configmap.yaml
@@ -2,7 +2,7 @@
 apiVersion: v1
 kind: ConfigMap
 metadata:
-  name: {{ .Release.Name }}-{{ .Chart.Name }}-delegation-nginx-config
+  name: {{ .Release.Name }}-{{ .Chart.Name }}-delegation-nginx-configmap
 data:
   nginx.conf: |
     worker_processes 1;
diff --git a/matrix-synapse/templates/matrix-delegation-nginx.deployment.yaml b/matrix-synapse/templates/matrix-delegation-nginx.deployment.yaml
index da3717a..3934c0c 100644
--- a/matrix-synapse/templates/matrix-delegation-nginx.deployment.yaml
+++ b/matrix-synapse/templates/matrix-delegation-nginx.deployment.yaml
@@ -2,18 +2,18 @@
 apiVersion: apps/v1
 kind: Deployment
 metadata:
-  name: {{ .Release.Name }}-{{ .Chart.Name }}-delegation-nginx
+  name: {{ .Release.Name }}-{{ .Chart.Name }}-delegation-nginx-deployment
   labels:
-    app: {{ .Release.Name }}-{{ .Chart.Name }}-delegation-nginx
+    app: {{ .Release.Name }}-{{ .Chart.Name }}-delegation-nginx-deployment
 spec:
   replicas: {{ include "matrix-synapse.replicas" (dict "scaleDown" .Values.scaleDown "replicas" .Values.matrix.delegation.replicas) }}
   selector:
     matchLabels:
-      app: {{ .Release.Name }}-{{ .Chart.Name }}-delegation-nginx
+      app: {{ .Release.Name }}-{{ .Chart.Name }}-delegation-nginx-deployment
   template:
     metadata:
       labels:
-        app: {{ .Release.Name }}-{{ .Chart.Name }}-delegation-nginx
+        app: {{ .Release.Name }}-{{ .Chart.Name }}-delegation-nginx-deployment
     spec:
       automountServiceAccountToken: false
       securityContext:
@@ -38,37 +38,18 @@ spec:
           resources:
             {{- include "matrix-synapse.resources" .Values.matrix.delegation.resources | nindent 12 }}
           readinessProbe:
-            httpGet:
-              path: /.well-known/matrix/server
-              port: http
-              scheme: HTTP
-            periodSeconds: 10
-            timeoutSeconds: 3
-            failureThreshold: 3
+            {{- toYaml .Values.matrix.delegation.readinessProbe | nindent 12 }}
           livenessProbe:
-            httpGet:
-              path: /.well-known/matrix/server
-              port: http
-              scheme: HTTP
-            periodSeconds: 10
-            timeoutSeconds: 3
-            failureThreshold: 3
-          # The startup probe gates liveness/readiness. Startup budget = 5s * 30 = 150s.
+            {{- toYaml .Values.matrix.delegation.livenessProbe | nindent 12 }}
           startupProbe:
-            httpGet:
-              path: /.well-known/matrix/server
-              port: http
-              scheme: HTTP
-            periodSeconds: 5
-            timeoutSeconds: 3
-            failureThreshold: 30
+            {{- toYaml .Values.matrix.delegation.startupProbe | nindent 12 }}
       volumes:
         - name: tmp
           emptyDir: {}
         - name: nginx-config
           configMap:
-            name: {{ .Release.Name }}-{{ .Chart.Name }}-delegation-nginx-config
+            name: {{ .Release.Name }}-{{ .Chart.Name }}-delegation-nginx-configmap
             items:
               - key: nginx.conf
                 path: nginx.conf
-{{- end }}
\ No newline at end of file
+{{- end }}
diff --git a/matrix-synapse/templates/matrix-delegation-nginx.service.yaml b/matrix-synapse/templates/matrix-delegation-nginx.service.yaml
index c644e95..c8ac50a 100644
--- a/matrix-synapse/templates/matrix-delegation-nginx.service.yaml
+++ b/matrix-synapse/templates/matrix-delegation-nginx.service.yaml
@@ -5,7 +5,7 @@ metadata:
   name: {{ .Release.Name }}-{{ .Chart.Name }}-delegation-service
 spec:
   selector:
-    app: {{ .Release.Name }}-{{ .Chart.Name }}-delegation-nginx
+    app: {{ .Release.Name }}-{{ .Chart.Name }}-delegation-nginx-deployment
   ports:
     - protocol: TCP
       port: 80
diff --git a/matrix-synapse/templates/matrix-synapse-config.secret.yaml b/matrix-synapse/templates/matrix-synapse-config.secret.yaml
index c48c1af..bd33c03 100644
--- a/matrix-synapse/templates/matrix-synapse-config.secret.yaml
+++ b/matrix-synapse/templates/matrix-synapse-config.secret.yaml
@@ -3,4 +3,4 @@ kind: OnePasswordItem
 metadata:
   name: {{ .Release.Name }}-{{ .Chart.Name }}-config-secret
 spec:
-  itemPath: {{ required "You must provide a configSecret Reference" .Values.matrix.configSecretRef }}
+  itemPath: {{ required "You must provide a configSecret Reference" .Values.secrets.configSecretRef }}
diff --git a/matrix-synapse/templates/matrix-synapse.ingress.yaml b/matrix-synapse/templates/matrix-synapse.ingress.yaml
index 893aa69..9e0ea7b 100644
--- a/matrix-synapse/templates/matrix-synapse.ingress.yaml
+++ b/matrix-synapse/templates/matrix-synapse.ingress.yaml
@@ -4,8 +4,11 @@ metadata:
   name: {{ .Release.Name }}-{{ .Chart.Name }}-ingress
   annotations:
     cert-manager.io/cluster-issuer: {{ required "A Cluster-Issuer must be provided" .Values.ingress.clusterIssuer }}
+    {{- with .Values.ingress.annotations }}
+    {{- toYaml . | nindent 4 }}
+    {{- end }}
 spec:
-  ingressClassName: nginx
+  ingressClassName: {{ .Values.ingress.className }}
   rules:
     - host: {{ required "A Domain/Host must be provided" .Values.ingress.domain }}
       http:
diff --git a/matrix-synapse/templates/matrix-synapse.sfs.yaml b/matrix-synapse/templates/matrix-synapse.sfs.yaml
index eade2d5..b72436e 100644
--- a/matrix-synapse/templates/matrix-synapse.sfs.yaml
+++ b/matrix-synapse/templates/matrix-synapse.sfs.yaml
@@ -18,52 +18,49 @@ spec:
     spec:
       automountServiceAccountToken: false
       securityContext:
-        fsGroup: 1000
-        fsGroupChangePolicy: Always
+        {{- toYaml .Values.matrix.securityContext.pod | nindent 8 }}
       containers:
         - name: "{{ .Release.Name }}-{{ .Chart.Name }}-container"
           image: "ghcr.io/element-hq/synapse:{{ .Chart.AppVersion }}"
+          securityContext:
+            {{- toYaml .Values.matrix.securityContext.container | nindent 12 }}
           env:
             - name: SYNAPSE_SERVER_NAME
               value: "{{ required "You must provide a Server-Name" .Values.matrix.serverName }}"
             - name: SYNAPSE_REPORT_STATS
               value: "no"
-            - name: UID
-              value: "1000"
-            - name: GID
-              value: "1000"
             - name: TZ
               value: "{{ .Values.matrix.timezone }}"
+            {{- range $value := .Values.matrix.env }}
+            {{- if $value.value }}
+            - name: {{ $value.name }}
+              value: {{ tpl $value.value $ }}
+            {{- else if $value.valueFrom }}
+            {{- if $value.valueFrom.secretKeyRef }}
+            - name: {{ $value.name }}
+              valueFrom:
+                secretKeyRef:
+                  name: {{ tpl $value.valueFrom.secretKeyRef.name $ }}
+                  key: {{ tpl $value.valueFrom.secretKeyRef.key $ }}
+            {{- else if $value.valueFrom.configMapKeyRef }}
+            - name: {{ $value.name }}
+              valueFrom:
+                configMapKeyRef:
+                  name: {{ tpl $value.valueFrom.configMapKeyRef.name $ }}
+                  key: {{ tpl $value.valueFrom.configMapKeyRef.key $ }}
+            {{- end }}
+            {{- end }}
+            {{- end }}
           ports:
             - name: http
               containerPort: 8008
               protocol: TCP
           readinessProbe:
-            httpGet:
-              path: /health
-              port: http
-              scheme: HTTP
-            periodSeconds: 10
-            timeoutSeconds: 5
-            failureThreshold: 3
+            {{- toYaml .Values.matrix.readinessProbe | nindent 12 }}
           livenessProbe:
-            httpGet:
-              path: /health
-              port: http
-              scheme: HTTP
-            periodSeconds: 10
-            timeoutSeconds: 5
-            failureThreshold: 3
-          # The startup probe gates liveness/readiness. Synapse can take a
-          # while to start (migrations, cache warmup): budget 10s * 30 = 300s.
+            {{- toYaml .Values.matrix.livenessProbe | nindent 12 }}
           startupProbe:
-            httpGet:
-              path: /health
-              port: http
-              scheme: HTTP
-            periodSeconds: 10
-            timeoutSeconds: 5
-            failureThreshold: 30
+            {{- toYaml .Values.matrix.startupProbe | nindent 12 }}
           resources:
             {{- include "matrix-synapse.resources" .Values.matrix.resources | nindent 12 }}
           volumeMounts:
@@ -76,7 +73,13 @@ spec:
             - name: matrix-synapse-config-secret
               mountPath: /data/homeserver.yaml
               subPath: homeserver.yaml
+            # Scratch space so the read-only root filesystem never blocks
+            # temp-file writes (e.g. URL-preview downloads).
+            - name: tmp
+              mountPath: /tmp
       volumes:
+        - name: tmp
+          emptyDir: {}
         - name: matrix-synapse-volume
           persistentVolumeClaim:
             claimName: {{ .Release.Name }}-{{ .Chart.Name }}-pvc
diff --git a/matrix-synapse/values.yaml b/matrix-synapse/values.yaml
index 1cad93d..0375764 100644
--- a/matrix-synapse/values.yaml
+++ b/matrix-synapse/values.yaml
@@ -4,13 +4,75 @@
 # Services stay in place; scaleDown: false brings the workloads back up.
 scaleDown: false
 
+secrets:
+  configSecretRef: null
+
 matrix:
   # Replica count for this workload; 0 is allowed and scales it down.
   # The chart-global scaleDown flag takes precedence.
   replicas: 1
   serverName: null
   timezone: UTC
-  configSecretRef: null
+  # The upstream image (ghcr.io/element-hq/synapse) only drops privileges
+  # itself (via gosu, driven by UID/GID env vars) when started as root; with
+  # an explicit non-root runAsUser it skips that step and runs directly as
+  # that user. Synapse writes to /data and /media_store (both on the PVC) and
+  # to /tmp (mounted as an emptyDir by the chart), so the root filesystem
+  # stays read-only. The uid/gid 1000 matches the previous gosu default, so
+  # existing PVC data stays accessible.
+  securityContext:
+    pod:
+      runAsNonRoot: true
+      runAsUser: 1000
+      runAsGroup: 1000
+      fsGroup: 1000
+      fsGroupChangePolicy: Always
+    container:
+      allowPrivilegeEscalation: false
+      readOnlyRootFilesystem: true
+      runAsNonRoot: true
+      capabilities:
+        drop:
+          - ALL
+  livenessProbe:
+    httpGet:
+      path: /health
+      port: http
+      scheme: HTTP
+    periodSeconds: 10
+    timeoutSeconds: 5
+    failureThreshold: 3
+  readinessProbe:
+    httpGet:
+      path: /health
+      port: http
+      scheme: HTTP
+    periodSeconds: 10
+    timeoutSeconds: 5
+    failureThreshold: 3
+  # The startup probe gates liveness/readiness. Synapse can take a
+  # while to start (migrations, cache warmup): budget 10s * 30 = 300s.
+  startupProbe:
+    httpGet:
+      path: /health
+      port: http
+      scheme: HTTP
+    periodSeconds: 10
+    timeoutSeconds: 5
+    failureThreshold: 30
+  # Extra environment variables, appended to the ones the chart always sets.
+  # Values are rendered through tpl; value, secretKeyRef and configMapKeyRef
+  # forms are supported.
+  env: []
+  resources:
+    # Limits are optional: memory and ephemeral-storage limits default to
+    # limitFactor x the request, an explicitly set limit always wins, and a
+    # CPU limit is only set when configured explicitly under "limits".
+    limitFactor: 3
+    requests:
+      memory: "1Gi"
+      cpu: "1"
+      ephemeralStorage: "1Gi"
   delegation:
     # Replica count for this workload; 0 is allowed and scales it down.
     # The chart-global scaleDown flag takes precedence.
@@ -37,6 +99,31 @@ matrix:
         capabilities:
           drop:
             - ALL
+    livenessProbe:
+      httpGet:
+        path: /.well-known/matrix/server
+        port: http
+        scheme: HTTP
+      periodSeconds: 10
+      timeoutSeconds: 3
+      failureThreshold: 3
+    readinessProbe:
+      httpGet:
+        path: /.well-known/matrix/server
+        port: http
+        scheme: HTTP
+      periodSeconds: 10
+      timeoutSeconds: 3
+      failureThreshold: 3
+    # The startup probe gates liveness/readiness. Startup budget = 5s * 30 = 150s.
+    startupProbe:
+      httpGet:
+        path: /.well-known/matrix/server
+        port: http
+        scheme: HTTP
+      periodSeconds: 5
+      timeoutSeconds: 3
+      failureThreshold: 30
     resources:
       # Limits are optional: memory and ephemeral-storage limits default to
       # limitFactor x the request, an explicitly set limit always wins, and a
@@ -46,15 +133,6 @@ matrix:
         memory: "64Mi"
         cpu: "125m"
         ephemeralStorage: "50Mi"
-  resources:
-    # Limits are optional: memory and ephemeral-storage limits default to
-    # limitFactor x the request, an explicitly set limit always wins, and a
-    # CPU limit is only set when configured explicitly under "limits".
-    limitFactor: 3
-    requests:
-      memory: "1Gi"
-      cpu: "1"
-      ephemeralStorage: "1Gi"
 
 storage:
   amount: 10Gi
@@ -63,3 +141,7 @@ storage:
 ingress:
   domain: null
   clusterIssuer: null
+  className: nginx
+  # Extra annotations for the Ingress; merged with the cert-manager
+  # cluster-issuer annotation the chart always sets.
+  annotations: {}