diff --git a/packages/registry/__tests__/addon-registry.test.js b/packages/registry/__tests__/addon-registry.test.js
index ca959d7c4e3..1f58d251e8a 100644
--- a/packages/registry/__tests__/addon-registry.test.js
+++ b/packages/registry/__tests__/addon-registry.test.js
@@ -230,6 +230,9 @@ describe('AddonRegistry - Project', () => {
       '@plone/volto/LanguageSwitcher': `${base}/src/customizations/LanguageSwitcher.js`,
       '@plone/volto/TSComponent': `${base}/src/customizations/TSComponent.jsx`,
       '@plone/volto/client': `${base}/src/customizations/client.js`,
+      // .cjs is shadowable, and the alias key keeps its extension because
+      // such modules are imported with it. See #8366.
+      '@plone/volto/constants/Languages.cjs': `${base}/src/customizations/constants/Languages.cjs`,
       '@plone/volto/routes': `${base}/src/customizations/routes.tsx`,
       'test-addon/testaddon': `${base}/src/custom-addons/test-addon/testaddon.js`,
       '@plone/volto/server': `${base}/src/customizations/server.jsx`,
diff --git a/packages/registry/__tests__/fixtures/test-volto-project/node_modules/@plone/volto/src/constants/Languages.cjs b/packages/registry/__tests__/fixtures/test-volto-project/node_modules/@plone/volto/src/constants/Languages.cjs
new file mode 100644
index 00000000000..b4234b4bfdc
--- /dev/null
+++ b/packages/registry/__tests__/fixtures/test-volto-project/node_modules/@plone/volto/src/constants/Languages.cjs
@@ -0,0 +1 @@
+module.exports = { en: 'English' };
diff --git a/packages/registry/__tests__/fixtures/test-volto-project/src/customizations/constants/Languages.cjs b/packages/registry/__tests__/fixtures/test-volto-project/src/customizations/constants/Languages.cjs
new file mode 100644
index 00000000000..fa2ddf64805
--- /dev/null
+++ b/packages/registry/__tests__/fixtures/test-volto-project/src/customizations/constants/Languages.cjs
@@ -0,0 +1 @@
+module.exports = { en: 'English', sv: 'Svenska' };
diff --git a/packages/registry/news/8366.bugfix b/packages/registry/news/8366.bugfix
new file mode 100644
index 00000000000..b8031d07265
--- /dev/null
+++ b/packages/registry/news/8366.bugfix
@@ -0,0 +1 @@
+Include `.cjs` and `.mjs` in the customizations glob so core modules with those extensions can be shadowed. @kunalKumar-13
diff --git a/packages/registry/src/addon-registry/addon-registry.ts b/packages/registry/src/addon-registry/addon-registry.ts
index c5cd1a241ad..29db2ea4244 100644
--- a/packages/registry/src/addon-registry/addon-registry.ts
+++ b/packages/registry/src/addon-registry/addon-registry.ts
@@ -743,7 +743,7 @@ class AddonRegistry {
 
       reg.forEach(({ customPath, name, sourcePath }) => {
         glob(
-          `${customPath}/**/*.*(svg|png|jpg|jpeg|gif|ico|less|js|jsx|ts|tsx)`,
+          `${customPath}/**/*.*(svg|png|jpg|jpeg|gif|ico|less|js|jsx|ts|tsx|cjs|mjs)`,
         ).map((filename) => {
           function changeFileExtension(filePath: string) {
             // Extract the current file extension