feat: Add support for nested secure keys.

Now we can use nested keys with dot separators like `themeVariables.fontSize` inside the `secure` config.

docs/config/setup/config/functions/addDirective.md

@@ -12,7 +12,7 @@
 
 > **addDirective**(`directive`): `void`
 
-Defined in: [packages/mermaid/src/config.ts:188](https://github.com/mermaid-js/mermaid/blob/master/packages/mermaid/src/config.ts#L188)
+Defined in: [packages/mermaid/src/config.ts:202](https://github.com/mermaid-js/mermaid/blob/master/packages/mermaid/src/config.ts#L202)
 
 Pushes in a directive to the configuration
 

docs/config/setup/config/functions/reset.md

@@ -12,7 +12,7 @@
 
 > **reset**(`config`): `void`
 
-Defined in: [packages/mermaid/src/config.ts:221](https://github.com/mermaid-js/mermaid/blob/master/packages/mermaid/src/config.ts#L221)
+Defined in: [packages/mermaid/src/config.ts:235](https://github.com/mermaid-js/mermaid/blob/master/packages/mermaid/src/config.ts#L235)
 
 ## reset
 

docs/config/setup/config/functions/sanitize.md

@@ -10,7 +10,7 @@
 
 # Function: sanitize()
 
-> **sanitize**(`options`): `void`
+> **sanitize**(`options`, `path`): `void`
 
 Defined in: [packages/mermaid/src/config.ts:146](https://github.com/mermaid-js/mermaid/blob/master/packages/mermaid/src/config.ts#L146)
 
@@ -31,6 +31,10 @@ options in-place
 
 The potential setConfig parameter
 
+### path
+
+`string`\[] = `[]`
+
 ## Returns
 
 `void`

packages/mermaid/src/config.spec.ts

@@ -34,6 +34,92 @@ describe('when working with site config', () => {
     expect(cfg.fontSize).toBe(config_0.fontSize);
     expect(cfg.securityLevel).toBe(config_0.securityLevel);
   });
+
+  it('should respect nested secure keys when applying directives', () => {
+    const config_0: MermaidConfig = {
+      fontFamily: 'foo-font',
+      themeVariables: {
+        fontSize: 16,
+        fontFamily: 'default-font',
+      },
+      secure: [
+        ...configApi.defaultConfig.secure!,
+        'themeVariables.fontSize',
+        'themeVariables.fontFamily',
+      ],
+    };
+    configApi.setSiteConfig(config_0);
+    const directive: MermaidConfig = {
+      fontFamily: 'baf',
+      themeVariables: {
+        fontSize: 24, // shouldn't be changed
+        fontFamily: 'new-font', // shouldn't be changed
+        primaryColor: '#ff0000', // should be allowed
+      },
+    };
+    const cfg: MermaidConfig = configApi.updateCurrentConfig(config_0, [directive]);
+    expect(cfg.fontFamily).toEqual(directive.fontFamily);
+    expect(cfg.themeVariables!.fontSize).toBe(config_0.themeVariables!.fontSize);
+    expect(cfg.themeVariables!.fontFamily).toBe(config_0.themeVariables!.fontFamily);
+    expect(cfg.themeVariables!.primaryColor).toBe(directive.themeVariables!.primaryColor);
+  });
+
+  it('should handle deeply nested secure keys', () => {
+    const config_0: MermaidConfig = {
+      flowchart: {
+        nodeSpacing: 50,
+        rankSpacing: 50,
+        curve: 'basis',
+        htmlLabels: true,
+        useMaxWidth: true,
+        diagramPadding: 8,
+      },
+      secure: [
+        ...configApi.defaultConfig.secure!,
+        'flowchart.nodeSpacing',
+        'flowchart.rankSpacing',
+      ],
+    };
+    configApi.setSiteConfig(config_0);
+    const directive: MermaidConfig = {
+      flowchart: {
+        nodeSpacing: 100, // shouldn't be changed
+        rankSpacing: 100, // shouldn't be changed
+        curve: 'linear', // should be allowed
+        htmlLabels: false, // should be allowed
+      },
+    };
+    const cfg: MermaidConfig = configApi.updateCurrentConfig(config_0, [directive]);
+    expect(cfg.flowchart!.nodeSpacing).toBe(config_0.flowchart!.nodeSpacing);
+    expect(cfg.flowchart!.rankSpacing).toBe(config_0.flowchart!.rankSpacing);
+    expect(cfg.flowchart!.curve).toBe(directive.flowchart!.curve);
+    expect(cfg.flowchart!.htmlLabels).toBe(directive.flowchart!.htmlLabels);
+    expect(cfg.flowchart!.diagramPadding).toBe(config_0.flowchart!.diagramPadding);
+  });
+
+  it('should handle mixed top-level and nested secure keys', () => {
+    const config_0: MermaidConfig = {
+      fontFamily: 'foo-font',
+      themeVariables: {
+        fontSize: 16,
+        primaryColor: '#000000',
+      },
+      secure: [...configApi.defaultConfig.secure!, 'fontFamily', 'themeVariables.fontSize'],
+    };
+    configApi.setSiteConfig(config_0);
+    const directive: MermaidConfig = {
+      fontFamily: 'new-font', // shouldn't be changed
+      themeVariables: {
+        fontSize: 24, // shouldn't be changed
+        primaryColor: '#ff0000', // should be allowed
+      },
+    };
+    const cfg: MermaidConfig = configApi.updateCurrentConfig(config_0, [directive]);
+    expect(cfg.fontFamily).toBe(config_0.fontFamily);
+    expect(cfg.themeVariables!.fontSize).toBe(config_0.themeVariables!.fontSize);
+    expect(cfg.themeVariables!.primaryColor).toBe(directive.themeVariables!.primaryColor);
+  });
+
   it('should allow setting partial options', () => {
     const defaultConfig = configApi.getConfig();
 

packages/mermaid/src/config.ts

@@ -143,17 +143,29 @@ export const getConfig = (): MermaidConfig => {
  *
  * @param options - The potential setConfig parameter
  */
-export const sanitize = (options: any) => {
+export const sanitize = (options: any, path: string[] = []) => {
   if (!options) {
     return;
   }
+
   // Checking that options are not in the list of excluded options
-  ['secure', ...(siteConfig.secure ?? [])].forEach((key) => {
-    if (Object.hasOwn(options, key)) {
-      // DO NOT attempt to print options[key] within `${}` as a malicious script
-      // can exploit the logger's attempt to stringify the value and execute arbitrary code
-      log.debug(`Denied attempt to modify a secure key ${key}`, options[key]);
-      delete options[key];
+  ['secure', ...(siteConfig.secure ?? [])].forEach((secureKey) => {
+    const securePath = secureKey.split('.');
+
+    // Check if current path matches the secure key path
+    if (path.length >= securePath.length - 1) {
+      const targetKey = securePath[securePath.length - 1];
+      const pathSuffix = path.slice(-(securePath.length - 1));
+      const pathPrefix = securePath.slice(0, -1);
+
+      const isMatch =
+        securePath.length === 1 ? path.length === 0 : pathSuffix.join('.') === pathPrefix.join('.');
+
+      if (isMatch && Object.hasOwn(options, targetKey)) {
+        const fullPath = path.length > 0 ? `${path.join('.')}.${secureKey}` : secureKey;
+        log.debug(`Denied attempt to modify a secure key ${fullPath}`, options[targetKey]);
+        delete options[targetKey];
+      }
     }
   });
 
@@ -163,6 +175,7 @@ export const sanitize = (options: any) => {
       delete options[key];
     }
   });
+
   // Check that there no attempts of xss, there should be no tags at all in the directive
   // blocking data urls as base64 urls can contain svg's with inline script tags
   Object.keys(options).forEach((key) => {
@@ -174,8 +187,9 @@ export const sanitize = (options: any) => {
     ) {
       delete options[key];
     }
-    if (typeof options[key] === 'object') {
-      sanitize(options[key]);
+    if (typeof options[key] === 'object' && options[key] !== null) {
+      // Recursively sanitize nested objects with updated path
+      sanitize(options[key], [...path, key]);
     }
   });
 };