diff --git a/docs/docs/api/CacheStore.md b/docs/docs/api/CacheStore.md
index 0f3b3eebc7f..00ceb960641 100644
--- a/docs/docs/api/CacheStore.md
+++ b/docs/docs/api/CacheStore.md
@@ -13,9 +13,9 @@ The `MemoryCacheStore` stores the responses in-memory.
 
 **Options**
 
-- `maxSize` - The maximum total size in bytes of all stored responses. Default `Infinity`.
-- `maxCount` - The maximum amount of responses to store. Default `Infinity`.
-- `maxEntrySize` - The maximum size in bytes that a response's body can be. If a response's body is greater than or equal to this, the response will not be cached. Default `Infinity`.
+- `maxSize` - The maximum total size in bytes of all stored responses. Default `104857600` (100MB).
+- `maxCount` - The maximum amount of responses to store. Default `1024`.
+- `maxEntrySize` - The maximum size in bytes that a response's body can be. If a response's body is greater than or equal to this, the response will not be cached. Default `5242880` (5MB).
 
 ### Getters
 
diff --git a/lib/cache/memory-cache-store.js b/lib/cache/memory-cache-store.js
index 2fb3dfabd19..dba29ae4de9 100644
--- a/lib/cache/memory-cache-store.js
+++ b/lib/cache/memory-cache-store.js
@@ -16,9 +16,9 @@ const { assertCacheKey, assertCacheValue } = require('../util/cache.js')
  * @extends {EventEmitter}
  */
 class MemoryCacheStore extends EventEmitter {
-  #maxCount = Infinity
-  #maxSize = Infinity
-  #maxEntrySize = Infinity
+  #maxCount = 1024
+  #maxSize = 104857600 // 100MB
+  #maxEntrySize = 5242880 // 5MB
 
   #size = 0
   #count = 0
diff --git a/test/cache-interceptor/memory-cache-store-tests.js b/test/cache-interceptor/memory-cache-store-tests.js
index 740cbdc31ce..e41fb9ad256 100644
--- a/test/cache-interceptor/memory-cache-store-tests.js
+++ b/test/cache-interceptor/memory-cache-store-tests.js
@@ -7,6 +7,56 @@ const { cacheStoreTests } = require('./cache-store-test-utils.js')
 
 cacheStoreTests(MemoryCacheStore)
 
+test('default limits prevent memory leaks', async () => {
+  const store = new MemoryCacheStore() // Uses new defaults
+
+  // Test that maxCount default (1024) is enforced
+  for (let i = 0; i < 1025; i++) {
+    const writeStream = store.createWriteStream(
+      { origin: 'test', path: `/test-${i}`, method: 'GET' },
+      {
+        statusCode: 200,
+        statusMessage: 'OK',
+        headers: {},
+        cachedAt: Date.now(),
+        staleAt: Date.now() + 60000,
+        deleteAt: Date.now() + 120000
+      }
+    )
+    writeStream.write('test data')
+    writeStream.end()
+  }
+
+  // Should be full after exceeding maxCount default of 1024
+  equal(store.isFull(), true, 'Store should be full after exceeding maxCount default')
+})
+
+test('default maxEntrySize prevents large entries', async () => {
+  const store = new MemoryCacheStore() // Uses new defaults
+
+  // Create entry larger than default maxEntrySize (5MB)
+  const largeData = Buffer.allocUnsafe(5242881) // 5MB + 1 byte
+
+  const writeStream = store.createWriteStream(
+    { origin: 'test', path: '/large', method: 'GET' },
+    {
+      statusCode: 200,
+      statusMessage: 'OK',
+      headers: {},
+      cachedAt: Date.now(),
+      staleAt: Date.now() + 60000,
+      deleteAt: Date.now() + 120000
+    }
+  )
+
+  writeStream.write(largeData)
+  writeStream.end()
+
+  // Entry should not be cached due to maxEntrySize limit
+  const result = store.get({ origin: 'test', path: '/large', method: 'GET', headers: {} })
+  equal(result, undefined, 'Large entry should not be cached due to maxEntrySize limit')
+})
+
 test('size getter returns correct total size', async () => {
   const store = new MemoryCacheStore()
   const testData = 'test data'