diff --git a/cyberchef/Chart.yaml b/cyberchef/Chart.yaml
index 9dc2155..7d10e46 100644
--- a/cyberchef/Chart.yaml
+++ b/cyberchef/Chart.yaml
@@ -5,7 +5,7 @@ icon: https://raw.githubusercontent.com/gchq/CyberChef/master/src/web/static/ima
 
 type: application
 
-version: 7.1.0+up11.4.0
+version: 8.0.0+up11.4.0
 appVersion: "11.4.0"
 
 maintainers:
diff --git a/cyberchef/templates/NOTES.txt b/cyberchef/templates/NOTES.txt
index 32682be..1ed0050 100644
--- a/cyberchef/templates/NOTES.txt
+++ b/cyberchef/templates/NOTES.txt
@@ -1,6 +1,8 @@
 {{- $replicas := include "cyberchef.replicas" (dict "scaleDown" .Values.scaleDown "replicas" .Values.cyberchef.replicas) -}}
 CyberChef {{ .Chart.AppVersion }} — release {{ .Release.Name }} in namespace {{ .Release.Namespace }}.
 
+{{- if .Values.ingress.enabled }}
+
 ACCESS
   https://{{ .Values.ingress.domain }}
 
@@ -11,11 +13,25 @@ ACCESS
 
   This chart has no secrets and no volumes — the two ingress values above are
   everything an installation needs.
+{{- else }}
+
+ACCESS — NO INGRESS
+  ingress.enabled is false, so this release has no Ingress and no certificate;
+  ingress.domain and ingress.clusterIssuer are not needed. The app is only
+  reachable inside the cluster, as
+  {{ .Release.Name }}-{{ .Chart.Name }}-service:80. To open it locally:
+
+    kubectl -n {{ .Release.Namespace }} port-forward svc/{{ .Release.Name }}-{{ .Chart.Name }}-service 8080:80
+
+  Then browse to http://localhost:8080. Set ingress.enabled=true together with
+  ingress.domain and ingress.clusterIssuer to publish it instead.
+{{- end }}
 {{ if eq $replicas "0" }}
 SCALED TO ZERO
-  {{ if .Values.scaleDown }}scaleDown: true{{ else }}cyberchef.replicas: 0{{ end }} — the deployment runs with replicas: 0, so the URL
-  above answers 503 until you set it back and upgrade again. Service and
-  Ingress stay in place, so the certificate is not re-issued.
+  {{ if .Values.scaleDown }}scaleDown: true{{ else }}cyberchef.replicas: 0{{ end }} — the deployment runs with replicas: 0, so the endpoint
+  above does not answer until you set it back and upgrade again. Service{{ if .Values.ingress.enabled }} and
+  Ingress stay in place, so the certificate is not re-issued.{{ else }} stays in
+  place.{{ end }}
 {{ end }}
 ANYONE WHO REACHES THE URL CAN USE IT
   CyberChef has no login, and this chart adds none. If it must not be open to
diff --git a/cyberchef/templates/_helpers.tpl b/cyberchef/templates/_helpers.tpl
index 9d7cd5e..8027859 100644
--- a/cyberchef/templates/_helpers.tpl
+++ b/cyberchef/templates/_helpers.tpl
@@ -114,3 +114,156 @@ template-chart is the reference implementation.
 1
 {{- end -}}
 {{- end -}}
+
+{{/*
+Merge a user-supplied values sub-tree onto a dict of chart defaults so that a
+null / empty override falls back to the defaults instead of erasing them.
+
+Input: dict "defaults" <dict> "given" <dict|nil> "path" <string, optional
+values path used in error messages>. Output: YAML of the merged dict (consume
+it with fromYaml).
+
+Why this exists (issue #99): Helm merges values maps recursively, but an
+override key written without children — e.g. a leftover
+
+  securityContext:
+
+after deleting its last remaining sub-key — is YAML null and replaces the
+whole default sub-tree. The container then renders with "securityContext:
+null": no readOnlyRootFilesystem, no dropped capabilities, no
+allowPrivilegeEscalation: false. The workload starts and reports healthy while
+being unhardened, so nothing points at the mistake. The same shape erases a
+probe (it disappears) or the resources block (no requests, no computed
+limits). This helper defines the opposite semantics: an empty block means
+"chart defaults apply".
+
+Rules:
+  - a nil "given" is treated as an empty dict (all defaults apply).
+  - a key whose override value is null keeps the default (nulls never delete).
+  - a key present in both as a map is merged recursively, so a partially
+    filled block only overrides the keys it actually sets.
+  - a scalar override for a key the defaults define as a map is rejected with
+    a message naming the values path, instead of failing later with a template
+    field error.
+  - any other set value wins as given, including an explicit false or 0 —
+    Helm's "default" and sprig's "mergeOverwrite" would both swallow those
+    zero values, hence the explicit kindIs "invalid" nil check.
+  - keys only present in the override are passed through unchanged.
+
+NOTE: like the helpers above, this is duplicated into every chart's
+templates/_helpers.tpl with the chart's name as define prefix, because charts
+in this repo deliberately have no dependencies.
+*/}}
+{{- define "cyberchef.defaultedDict" -}}
+{{- $defaults := .defaults | default dict -}}
+{{- $given := .given -}}
+{{- $path := .path | default "value" -}}
+{{- if kindIs "invalid" $given -}}
+{{- $given = dict -}}
+{{- end -}}
+{{- if not (kindIs "map" $given) -}}
+{{- fail (printf "%s must be a mapping or null, got %s (%v)" $path (kindOf $given) $given) -}}
+{{- end -}}
+{{- $out := deepCopy $defaults -}}
+{{- range $key, $value := $given -}}
+{{- if not (kindIs "invalid" $value) -}}
+{{- $default := index $defaults $key -}}
+{{- if and (kindIs "map" $value) (kindIs "map" $default) -}}
+{{- $_ := set $out $key (fromYaml (include "cyberchef.defaultedDict" (dict "defaults" $default "given" $value "path" (printf "%s.%s" $path $key)))) -}}
+{{- else if kindIs "map" $default -}}
+{{- fail (printf "%s.%s must be a mapping or null, got %s (%v)" $path $key (kindOf $value) $value) -}}
+{{- else -}}
+{{- $_ := set $out $key $value -}}
+{{- end -}}
+{{- end -}}
+{{- end -}}
+{{- toYaml $out -}}
+{{- end -}}
+
+{{/*
+Pick one sub-block out of a values block that may itself be null.
+
+Input: dict "block" <dict|nil> "key" <string> "path" <string>.
+Returns YAML of dict "value" <the sub-block, may be nil>, after rejecting a
+non-mapping block with a message that names the values path. Needed because
+".Values.cyberchef.securityContext" can itself be erased.
+*/}}
+{{- define "cyberchef.subBlock" -}}
+{{- $block := .block -}}
+{{- if kindIs "invalid" $block -}}
+{{- $block = dict -}}
+{{- end -}}
+{{- if not (kindIs "map" $block) -}}
+{{- fail (printf "%s must be a mapping or null, got %s (%v)" .path (kindOf $block) $block) -}}
+{{- end -}}
+{{- toYaml (dict "value" (index $block .key)) -}}
+{{- end -}}
+
+{{/*
+The effective security contexts, probes and resources (issue #99).
+
+The defaults below MUST stay in sync with the corresponding blocks in
+values.yaml, which stays the documented, user-facing place for them; this copy
+is only the fallback for the case where an override has erased the block.
+
+The probes address the container port by its name ("http"), so a rebuilt
+default probe needs no further context.
+*/}}
+{{- define "cyberchef.podSecurityContext" -}}
+{{- $given := (fromYaml (include "cyberchef.subBlock" (dict "block" . "key" "pod" "path" "cyberchef.securityContext"))).value -}}
+{{- $defaults := dict
+      "runAsNonRoot" true
+      "runAsUser" 101
+      "runAsGroup" 101 -}}
+{{- include "cyberchef.defaultedDict" (dict "defaults" $defaults "given" $given "path" "cyberchef.securityContext.pod") -}}
+{{- end -}}
+
+{{- define "cyberchef.containerSecurityContext" -}}
+{{- $given := (fromYaml (include "cyberchef.subBlock" (dict "block" . "key" "container" "path" "cyberchef.securityContext"))).value -}}
+{{- $defaults := dict
+      "allowPrivilegeEscalation" false
+      "readOnlyRootFilesystem" true
+      "runAsNonRoot" true
+      "capabilities" (dict "drop" (list "ALL")) -}}
+{{- include "cyberchef.defaultedDict" (dict "defaults" $defaults "given" $given "path" "cyberchef.securityContext.container") -}}
+{{- end -}}
+
+{{- define "cyberchef.livenessProbe" -}}
+{{- $defaults := dict
+      "httpGet" (dict "path" "/" "port" "http")
+      "periodSeconds" 10
+      "timeoutSeconds" 5
+      "failureThreshold" 3 -}}
+{{- include "cyberchef.defaultedDict" (dict "defaults" $defaults "given" . "path" "cyberchef.livenessProbe") -}}
+{{- end -}}
+
+{{- define "cyberchef.readinessProbe" -}}
+{{- $defaults := dict
+      "httpGet" (dict "path" "/" "port" "http")
+      "periodSeconds" 10
+      "timeoutSeconds" 5
+      "failureThreshold" 3 -}}
+{{- include "cyberchef.defaultedDict" (dict "defaults" $defaults "given" . "path" "cyberchef.readinessProbe") -}}
+{{- end -}}
+
+{{- define "cyberchef.startupProbe" -}}
+{{- $defaults := dict
+      "httpGet" (dict "path" "/" "port" "http")
+      "periodSeconds" 5
+      "timeoutSeconds" 5
+      "failureThreshold" 30 -}}
+{{- include "cyberchef.defaultedDict" (dict "defaults" $defaults "given" . "path" "cyberchef.startupProbe") -}}
+{{- end -}}
+
+{{/*
+The effective resources block, fed into the resources helper above so that an
+erased "resources:" still yields the chart's requests and computed limits
+instead of a container without any resource accounting.
+*/}}
+{{- define "cyberchef.effectiveResources" -}}
+{{- $defaults := dict
+      "limitFactor" 3
+      "requests" (dict "cpu" 0.1 "memory" "512Mi" "ephemeralStorage" "10Mi") -}}
+{{- $merged := fromYaml (include "cyberchef.defaultedDict" (dict "defaults" $defaults "given" . "path" "cyberchef.resources")) -}}
+{{- include "cyberchef.resources" $merged -}}
+{{- end -}}
diff --git a/cyberchef/templates/cyberchef.deployment.yaml b/cyberchef/templates/cyberchef.deployment.yaml
index aac23d8..9f29d37 100644
--- a/cyberchef/templates/cyberchef.deployment.yaml
+++ b/cyberchef/templates/cyberchef.deployment.yaml
@@ -17,7 +17,7 @@ spec:
     spec:
       automountServiceAccountToken: false
       securityContext:
-        {{- toYaml .Values.cyberchef.securityContext.pod | nindent 8 }}
+        {{- include "cyberchef.podSecurityContext" .Values.cyberchef.securityContext | nindent 8 }}
       containers:
         - name: {{ .Release.Name }}-{{ .Chart.Name }}-deployment
           image: "ghcr.io/gchq/cyberchef:{{ .Chart.AppVersion }}"
@@ -46,7 +46,7 @@ spec:
             {{- end }}
           {{- end }}
           securityContext:
-            {{- toYaml .Values.cyberchef.securityContext.container | nindent 12 }}
+            {{- include "cyberchef.containerSecurityContext" .Values.cyberchef.securityContext | nindent 12 }}
           volumeMounts:
             # nginx-unprivileged keeps its pid file and temp/cache dirs under
             # /tmp, which needs to be writable with a read-only root filesystem.
@@ -57,13 +57,13 @@ spec:
               protocol: TCP
               name: http
           livenessProbe:
-            {{- toYaml .Values.cyberchef.livenessProbe | nindent 12 }}
+            {{- include "cyberchef.livenessProbe" .Values.cyberchef.livenessProbe | nindent 12 }}
           readinessProbe:
-            {{- toYaml .Values.cyberchef.readinessProbe | nindent 12 }}
+            {{- include "cyberchef.readinessProbe" .Values.cyberchef.readinessProbe | nindent 12 }}
           startupProbe:
-            {{- toYaml .Values.cyberchef.startupProbe | nindent 12 }}
+            {{- include "cyberchef.startupProbe" .Values.cyberchef.startupProbe | nindent 12 }}
           resources:
-            {{- include "cyberchef.resources" .Values.cyberchef.resources | nindent 12 }}
+            {{- include "cyberchef.effectiveResources" .Values.cyberchef.resources | nindent 12 }}
       volumes:
         - name: tmp
           emptyDir: {}
diff --git a/cyberchef/templates/cyberchef.ingress.yaml b/cyberchef/templates/cyberchef.ingress.yaml
index 6c22769..a9387ff 100644
--- a/cyberchef/templates/cyberchef.ingress.yaml
+++ b/cyberchef/templates/cyberchef.ingress.yaml
@@ -1,3 +1,4 @@
+{{- if .Values.ingress.enabled }}
 apiVersion: networking.k8s.io/v1
 kind: Ingress
 metadata:
@@ -24,3 +25,4 @@ spec:
     - hosts:
         - {{ required "A Domain/Host must be provided" .Values.ingress.domain }}
       secretName: tls-{{ .Release.Name }}-{{ .Chart.Name }}-ingress
+{{- end }}
diff --git a/cyberchef/values.schema.json b/cyberchef/values.schema.json
index ea39ecd..4e056b7 100644
--- a/cyberchef/values.schema.json
+++ b/cyberchef/values.schema.json
@@ -65,7 +65,8 @@
   },
   "definitions": {
     "resources": {
-      "type": "object",
+      "description": "May be null / empty: the chart then falls back to its default requests and computed limits (issue #99) instead of rendering a container without resource accounting.",
+      "type": ["object", "null"],
       "additionalProperties": false,
       "properties": {
         "limitFactor": {
@@ -81,7 +82,7 @@
       }
     },
     "resourceList": {
-      "type": "object",
+      "type": ["object", "null"],
       "additionalProperties": false,
       "properties": {
         "cpu": {
@@ -140,22 +141,23 @@
       }
     },
     "securityContext": {
-      "type": "object",
+      "description": "May be null / empty at any level: the chart then falls back to its hardening defaults (issue #99) instead of rendering an unhardened workload.",
+      "type": ["object", "null"],
       "additionalProperties": false,
       "properties": {
         "pod": {
-          "description": "Rendered verbatim as the pod's securityContext; kept open because the chart does not interpret it.",
-          "type": "object"
+          "description": "Merged onto the chart's pod hardening defaults and rendered as the pod's securityContext; kept open because the chart does not interpret the individual fields.",
+          "type": ["object", "null"]
         },
         "container": {
-          "description": "Rendered verbatim as the container's securityContext; kept open because the chart does not interpret it.",
-          "type": "object"
+          "description": "Merged onto the chart's container hardening defaults and rendered as the container's securityContext; kept open because the chart does not interpret the individual fields.",
+          "type": ["object", "null"]
         }
       }
     },
     "probe": {
-      "description": "Rendered verbatim as a container probe; kept open because the chart does not interpret it.",
-      "type": "object"
+      "description": "Merged onto the chart's probe defaults and rendered as a container probe; kept open because the chart does not interpret the individual fields. May be null / empty, which means the defaults apply (issue #99) rather than the probe disappearing.",
+      "type": ["object", "null"]
     }
   }
 }
diff --git a/cyberchef/values.yaml b/cyberchef/values.yaml
index c891758..deebe83 100644
--- a/cyberchef/values.yaml
+++ b/cyberchef/values.yaml
@@ -59,6 +59,9 @@ cyberchef:
       ephemeralStorage: 10Mi
 
 ingress:
+  # Set to false to omit the Ingress entirely (the required domain and
+  # clusterIssuer values are then not needed either, because they are only
+  # read inside the Ingress template).
   enabled: true
   clusterIssuer: null
   domain: null