diff --git a/CHANGELOG.md b/CHANGELOG.md
index cfecf876d9..89abced7fc 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -6,7 +6,7 @@ Note that the only difference between `v2` and `v3` of the CodeQL Action is the
 
 ## [UNRELEASED]
 
-No user facing changes.
+- Update default CodeQL bundle version to 2.18.4. [#2471](https://github.com/github/codeql-action/pull/2471)
 
 ## 3.26.6 - 29 Aug 2024
 
diff --git a/lib/defaults.json b/lib/defaults.json
index f3f4efa834..04f75f203d 100644
--- a/lib/defaults.json
+++ b/lib/defaults.json
@@ -1,6 +1,6 @@
 {
-    "bundleVersion": "codeql-bundle-v2.18.3",
-    "cliVersion": "2.18.3",
-    "priorBundleVersion": "codeql-bundle-v2.18.2",
-    "priorCliVersion": "2.18.2"
+    "bundleVersion": "codeql-bundle-v2.18.4",
+    "cliVersion": "2.18.4",
+    "priorBundleVersion": "codeql-bundle-v2.18.3",
+    "priorCliVersion": "2.18.3"
 }
diff --git a/src/defaults.json b/src/defaults.json
index a979a4f047..5de09cf601 100644
--- a/src/defaults.json
+++ b/src/defaults.json
@@ -1,6 +1,6 @@
 {
-  "bundleVersion": "codeql-bundle-v2.18.3",
-  "cliVersion": "2.18.3",
-  "priorBundleVersion": "codeql-bundle-v2.18.2",
-  "priorCliVersion": "2.18.2"
+  "bundleVersion": "codeql-bundle-v2.18.4",
+  "cliVersion": "2.18.4",
+  "priorBundleVersion": "codeql-bundle-v2.18.3",
+  "priorCliVersion": "2.18.3"
 }