diff --git a/internal/handlers/app.go b/internal/handlers/app.go
index 492fa9a..5c58da4 100644
--- a/internal/handlers/app.go
+++ b/internal/handlers/app.go
@@ -4,6 +4,8 @@ import (
 	"context"
 	"database/sql"
 	"encoding/json"
+	"errors"
+	"fmt"
 	"net/http"
 	"os"
 	"path/filepath"
@@ -1116,6 +1118,207 @@ func (h *Handlers) HandlePortDelete() http.HandlerFunc {
 	}
 }
 
+// ErrVolumePathEmpty is returned when a volume path is empty.
+var ErrVolumePathEmpty = errors.New("path must not be empty")
+
+// ErrVolumePathNotAbsolute is returned when a volume path is not absolute.
+var ErrVolumePathNotAbsolute = errors.New("path must be absolute")
+
+// ErrVolumePathNotClean is returned when a volume path is not clean.
+var ErrVolumePathNotClean = errors.New("path must be clean")
+
+// ValidateVolumePath checks that a path is absolute and clean.
+func ValidateVolumePath(p string) error {
+	if p == "" {
+		return ErrVolumePathEmpty
+	}
+
+	if !filepath.IsAbs(p) {
+		return ErrVolumePathNotAbsolute
+	}
+
+	cleaned := filepath.Clean(p)
+	if cleaned != p {
+		return fmt.Errorf("%w (expected %q)", ErrVolumePathNotClean, cleaned)
+	}
+
+	return nil
+}
+
+// HandleEnvVarEdit handles editing an existing environment variable.
+func (h *Handlers) HandleEnvVarEdit() http.HandlerFunc {
+	return func(writer http.ResponseWriter, request *http.Request) {
+		appID := chi.URLParam(request, "id")
+		envVarIDStr := chi.URLParam(request, "varID")
+
+		envVarID, parseErr := strconv.ParseInt(envVarIDStr, 10, 64)
+		if parseErr != nil {
+			http.NotFound(writer, request)
+
+			return
+		}
+
+		envVar, findErr := models.FindEnvVar(request.Context(), h.db, envVarID)
+		if findErr != nil || envVar == nil || envVar.AppID != appID {
+			http.NotFound(writer, request)
+
+			return
+		}
+
+		formErr := request.ParseForm()
+		if formErr != nil {
+			http.Error(writer, "Bad Request", http.StatusBadRequest)
+
+			return
+		}
+
+		key := request.FormValue("key")
+		value := request.FormValue("value")
+
+		if key == "" || value == "" {
+			http.Redirect(writer, request, "/apps/"+appID, http.StatusSeeOther)
+
+			return
+		}
+
+		envVar.Key = key
+		envVar.Value = value
+
+		saveErr := envVar.Save(request.Context())
+		if saveErr != nil {
+			h.log.Error("failed to update env var", "error", saveErr)
+		}
+
+		http.Redirect(
+			writer,
+			request,
+			"/apps/"+appID+"?success=env-updated",
+			http.StatusSeeOther,
+		)
+	}
+}
+
+// HandleLabelEdit handles editing an existing label.
+func (h *Handlers) HandleLabelEdit() http.HandlerFunc {
+	return func(writer http.ResponseWriter, request *http.Request) {
+		appID := chi.URLParam(request, "id")
+		labelIDStr := chi.URLParam(request, "labelID")
+
+		labelID, parseErr := strconv.ParseInt(labelIDStr, 10, 64)
+		if parseErr != nil {
+			http.NotFound(writer, request)
+
+			return
+		}
+
+		label, findErr := models.FindLabel(request.Context(), h.db, labelID)
+		if findErr != nil || label == nil || label.AppID != appID {
+			http.NotFound(writer, request)
+
+			return
+		}
+
+		formErr := request.ParseForm()
+		if formErr != nil {
+			http.Error(writer, "Bad Request", http.StatusBadRequest)
+
+			return
+		}
+
+		key := request.FormValue("key")
+		value := request.FormValue("value")
+
+		if key == "" || value == "" {
+			http.Redirect(writer, request, "/apps/"+appID, http.StatusSeeOther)
+
+			return
+		}
+
+		label.Key = key
+		label.Value = value
+
+		saveErr := label.Save(request.Context())
+		if saveErr != nil {
+			h.log.Error("failed to update label", "error", saveErr)
+		}
+
+		http.Redirect(writer, request, "/apps/"+appID, http.StatusSeeOther)
+	}
+}
+
+// HandleVolumeEdit handles editing an existing volume mount.
+func (h *Handlers) HandleVolumeEdit() http.HandlerFunc {
+	return func(writer http.ResponseWriter, request *http.Request) {
+		appID := chi.URLParam(request, "id")
+		volumeIDStr := chi.URLParam(request, "volumeID")
+
+		volumeID, parseErr := strconv.ParseInt(volumeIDStr, 10, 64)
+		if parseErr != nil {
+			http.NotFound(writer, request)
+
+			return
+		}
+
+		volume, findErr := models.FindVolume(request.Context(), h.db, volumeID)
+		if findErr != nil || volume == nil || volume.AppID != appID {
+			http.NotFound(writer, request)
+
+			return
+		}
+
+		formErr := request.ParseForm()
+		if formErr != nil {
+			http.Error(writer, "Bad Request", http.StatusBadRequest)
+
+			return
+		}
+
+		hostPath := request.FormValue("host_path")
+		containerPath := request.FormValue("container_path")
+		readOnly := request.FormValue("readonly") == "1"
+
+		if hostPath == "" || containerPath == "" {
+			http.Redirect(writer, request, "/apps/"+appID, http.StatusSeeOther)
+
+			return
+		}
+
+		pathErr := validateVolumePaths(hostPath, containerPath)
+		if pathErr != nil {
+			h.log.Error("invalid volume path", "error", pathErr)
+			http.Redirect(writer, request, "/apps/"+appID, http.StatusSeeOther)
+
+			return
+		}
+
+		volume.HostPath = hostPath
+		volume.ContainerPath = containerPath
+		volume.ReadOnly = readOnly
+
+		saveErr := volume.Save(request.Context())
+		if saveErr != nil {
+			h.log.Error("failed to update volume", "error", saveErr)
+		}
+
+		http.Redirect(writer, request, "/apps/"+appID, http.StatusSeeOther)
+	}
+}
+
+// validateVolumePaths validates both host and container paths for a volume.
+func validateVolumePaths(hostPath, containerPath string) error {
+	hostErr := ValidateVolumePath(hostPath)
+	if hostErr != nil {
+		return fmt.Errorf("host path: %w", hostErr)
+	}
+
+	containerErr := ValidateVolumePath(containerPath)
+	if containerErr != nil {
+		return fmt.Errorf("container path: %w", containerErr)
+	}
+
+	return nil
+}
+
 // formatDeployKey formats an SSH public key with a descriptive comment.
 // Format: ssh-ed25519 AAAA... upaas_2025-01-15_myapp
 func formatDeployKey(pubKey string, createdAt time.Time, appName string) string {
diff --git a/internal/handlers/volume_validation_test.go b/internal/handlers/volume_validation_test.go
new file mode 100644
index 0000000..9389fe3
--- /dev/null
+++ b/internal/handlers/volume_validation_test.go
@@ -0,0 +1,34 @@
+package handlers //nolint:testpackage // tests exported ValidateVolumePath function
+
+import "testing"
+
+func TestValidateVolumePath(t *testing.T) {
+	t.Parallel()
+
+	tests := []struct {
+		name    string
+		path    string
+		wantErr bool
+	}{
+		{"valid absolute path", "/data/myapp", false},
+		{"root path", "/", false},
+		{"empty path", "", true},
+		{"relative path", "data/myapp", true},
+		{"path with dotdot", "/data/../etc", true},
+		{"path with trailing slash", "/data/", true},
+		{"path with double slash", "/data//myapp", true},
+		{"single dot path", ".", true},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			t.Parallel()
+
+			err := ValidateVolumePath(tt.path)
+			if (err != nil) != tt.wantErr {
+				t.Errorf("ValidateVolumePath(%q) error = %v, wantErr %v",
+					tt.path, err, tt.wantErr)
+			}
+		})
+	}
+}
diff --git a/internal/server/routes.go b/internal/server/routes.go
index 3acadea..fc4cc7f 100644
--- a/internal/server/routes.go
+++ b/internal/server/routes.go
@@ -82,14 +82,17 @@ func (s *Server) SetupRoutes() {
 
 		// Environment variables
 		r.Post("/apps/{id}/env-vars", s.handlers.HandleEnvVarAdd())
+		r.Post("/apps/{id}/env-vars/{varID}/edit", s.handlers.HandleEnvVarEdit())
 		r.Post("/apps/{id}/env-vars/{varID}/delete", s.handlers.HandleEnvVarDelete())
 
 		// Labels
 		r.Post("/apps/{id}/labels", s.handlers.HandleLabelAdd())
+		r.Post("/apps/{id}/labels/{labelID}/edit", s.handlers.HandleLabelEdit())
 		r.Post("/apps/{id}/labels/{labelID}/delete", s.handlers.HandleLabelDelete())
 
 		// Volumes
 		r.Post("/apps/{id}/volumes", s.handlers.HandleVolumeAdd())
+		r.Post("/apps/{id}/volumes/{volumeID}/edit", s.handlers.HandleVolumeEdit())
 		r.Post("/apps/{id}/volumes/{volumeID}/delete", s.handlers.HandleVolumeDelete())
 
 		// Ports
diff --git a/templates/app_detail.html b/templates/app_detail.html
index 14fb91e..ce2b812 100644
--- a/templates/app_detail.html
+++ b/templates/app_detail.html
@@ -106,15 +106,34 @@
                 </thead>
                 <tbody class="table-body">
                     {{range .EnvVars}}
-                    <tr>
-                        <td class="font-mono font-medium">{{.Key}}</td>
-                        <td class="font-mono text-gray-500">{{.Value}}</td>
-                        <td class="text-right">
-                            <form method="POST" action="/apps/{{$.App.ID}}/env/{{.ID}}/delete" class="inline" x-data="confirmAction('Delete this environment variable?')" @submit="confirm($event)">
-                {{ .CSRFField }}
-                                <button type="submit" class="text-error-500 hover:text-error-700 text-sm">Delete</button>
-                            </form>
-                        </td>
+                    <tr x-data="{ editing: false }">
+                        <template x-if="!editing">
+                            <td class="font-mono font-medium">{{.Key}}</td>
+                        </template>
+                        <template x-if="!editing">
+                            <td class="font-mono text-gray-500">{{.Value}}</td>
+                        </template>
+                        <template x-if="!editing">
+                            <td class="text-right">
+                                <button @click="editing = true" class="text-primary-600 hover:text-primary-800 text-sm mr-2">Edit</button>
+                                <form method="POST" action="/apps/{{$.App.ID}}/env-vars/{{.ID}}/delete" class="inline" x-data="confirmAction('Delete this environment variable?')" @submit="confirm($event)">
+                                    {{ $.CSRFField }}
+                                    <button type="submit" class="text-error-500 hover:text-error-700 text-sm">Delete</button>
+                                </form>
+                            </td>
+                        </template>
+                        <template x-if="editing">
+                            <td colspan="3">
+                                <form method="POST" action="/apps/{{$.App.ID}}/env-vars/{{.ID}}/edit" class="flex gap-2 items-center">
+                                    {{ $.CSRFField }}
+                                    <input type="text" name="key" value="{{.Key}}" required class="input flex-1 font-mono text-sm">
+                                    <input type="text" name="value" value="{{.Value}}" required class="input flex-1 font-mono text-sm">
+                                    <button type="submit" class="btn-primary text-sm">Save</button>
+                                    <button type="button" @click="editing = false" class="text-gray-500 hover:text-gray-700 text-sm">Cancel</button>
+                                </form>
+                                <p class="text-xs text-amber-600 mt-1">⚠ Container restart needed after env var changes.</p>
+                            </td>
+                        </template>
                     </tr>
                     {{end}}
                 </tbody>
@@ -151,15 +170,33 @@
                         </td>
                     </tr>
                     {{range .Labels}}
-                    <tr>
-                        <td class="font-mono font-medium">{{.Key}}</td>
-                        <td class="font-mono text-gray-500">{{.Value}}</td>
-                        <td class="text-right">
-                            <form method="POST" action="/apps/{{$.App.ID}}/labels/{{.ID}}/delete" class="inline" x-data="confirmAction('Delete this label?')" @submit="confirm($event)">
-                {{ .CSRFField }}
-                                <button type="submit" class="text-error-500 hover:text-error-700 text-sm">Delete</button>
-                            </form>
-                        </td>
+                    <tr x-data="{ editing: false }">
+                        <template x-if="!editing">
+                            <td class="font-mono font-medium">{{.Key}}</td>
+                        </template>
+                        <template x-if="!editing">
+                            <td class="font-mono text-gray-500">{{.Value}}</td>
+                        </template>
+                        <template x-if="!editing">
+                            <td class="text-right">
+                                <button @click="editing = true" class="text-primary-600 hover:text-primary-800 text-sm mr-2">Edit</button>
+                                <form method="POST" action="/apps/{{$.App.ID}}/labels/{{.ID}}/delete" class="inline" x-data="confirmAction('Delete this label?')" @submit="confirm($event)">
+                                    {{ $.CSRFField }}
+                                    <button type="submit" class="text-error-500 hover:text-error-700 text-sm">Delete</button>
+                                </form>
+                            </td>
+                        </template>
+                        <template x-if="editing">
+                            <td colspan="3">
+                                <form method="POST" action="/apps/{{$.App.ID}}/labels/{{.ID}}/edit" class="flex gap-2 items-center">
+                                    {{ $.CSRFField }}
+                                    <input type="text" name="key" value="{{.Key}}" required class="input flex-1 font-mono text-sm">
+                                    <input type="text" name="value" value="{{.Value}}" required class="input flex-1 font-mono text-sm">
+                                    <button type="submit" class="btn-primary text-sm">Save</button>
+                                    <button type="button" @click="editing = false" class="text-gray-500 hover:text-gray-700 text-sm">Cancel</button>
+                                </form>
+                            </td>
+                        </template>
                     </tr>
                     {{end}}
                 </tbody>
@@ -189,22 +226,46 @@
                 </thead>
                 <tbody class="table-body">
                     {{range .Volumes}}
-                    <tr>
-                        <td class="font-mono">{{.HostPath}}</td>
-                        <td class="font-mono">{{.ContainerPath}}</td>
-                        <td>
-                            {{if .ReadOnly}}
-                            <span class="badge-neutral">Read-only</span>
-                            {{else}}
-                            <span class="badge-info">Read-write</span>
-                            {{end}}
-                        </td>
-                        <td class="text-right">
-                            <form method="POST" action="/apps/{{$.App.ID}}/volumes/{{.ID}}/delete" class="inline" x-data="confirmAction('Delete this volume mount?')" @submit="confirm($event)">
-                {{ .CSRFField }}
-                                <button type="submit" class="text-error-500 hover:text-error-700 text-sm">Delete</button>
-                            </form>
-                        </td>
+                    <tr x-data="{ editing: false }">
+                        <template x-if="!editing">
+                            <td class="font-mono">{{.HostPath}}</td>
+                        </template>
+                        <template x-if="!editing">
+                            <td class="font-mono">{{.ContainerPath}}</td>
+                        </template>
+                        <template x-if="!editing">
+                            <td>
+                                {{if .ReadOnly}}
+                                <span class="badge-neutral">Read-only</span>
+                                {{else}}
+                                <span class="badge-info">Read-write</span>
+                                {{end}}
+                            </td>
+                        </template>
+                        <template x-if="!editing">
+                            <td class="text-right">
+                                <button @click="editing = true" class="text-primary-600 hover:text-primary-800 text-sm mr-2">Edit</button>
+                                <form method="POST" action="/apps/{{$.App.ID}}/volumes/{{.ID}}/delete" class="inline" x-data="confirmAction('Delete this volume mount?')" @submit="confirm($event)">
+                                    {{ $.CSRFField }}
+                                    <button type="submit" class="text-error-500 hover:text-error-700 text-sm">Delete</button>
+                                </form>
+                            </td>
+                        </template>
+                        <template x-if="editing">
+                            <td colspan="4">
+                                <form method="POST" action="/apps/{{$.App.ID}}/volumes/{{.ID}}/edit" class="flex gap-2 items-center">
+                                    {{ $.CSRFField }}
+                                    <input type="text" name="host_path" value="{{.HostPath}}" required class="input flex-1 font-mono text-sm" placeholder="/host/path">
+                                    <input type="text" name="container_path" value="{{.ContainerPath}}" required class="input flex-1 font-mono text-sm" placeholder="/container/path">
+                                    <label class="flex items-center gap-1 text-sm text-gray-600 whitespace-nowrap">
+                                        <input type="checkbox" name="readonly" value="1" {{if .ReadOnly}}checked{{end}} class="rounded border-gray-300 text-primary-600 focus:ring-primary-500">
+                                        RO
+                                    </label>
+                                    <button type="submit" class="btn-primary text-sm">Save</button>
+                                    <button type="button" @click="editing = false" class="text-gray-500 hover:text-gray-700 text-sm">Cancel</button>
+                                </form>
+                            </td>
+                        </template>
                     </tr>
                     {{end}}
                 </tbody>