diff --git a/CHANGELOG.md b/CHANGELOG.md
index e53788a3de..0806ad3445 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 2.18.3. [#2449](https://github.com/github/codeql-action/pull/2449)
 
 ## 3.26.5 - 23 Aug 2024
 
diff --git a/lib/defaults.json b/lib/defaults.json
index 29638bb159..f3f4efa834 100644
--- a/lib/defaults.json
+++ b/lib/defaults.json
@@ -1,6 +1,6 @@
 {
-    "bundleVersion": "codeql-bundle-v2.18.2",
-    "cliVersion": "2.18.2",
-    "priorBundleVersion": "codeql-bundle-v2.18.1",
-    "priorCliVersion": "2.18.1"
+    "bundleVersion": "codeql-bundle-v2.18.3",
+    "cliVersion": "2.18.3",
+    "priorBundleVersion": "codeql-bundle-v2.18.2",
+    "priorCliVersion": "2.18.2"
 }
diff --git a/src/defaults.json b/src/defaults.json
index 5c63e93bc9..a979a4f047 100644
--- a/src/defaults.json
+++ b/src/defaults.json
@@ -1,6 +1,6 @@
 {
-  "bundleVersion": "codeql-bundle-v2.18.2",
-  "cliVersion": "2.18.2",
-  "priorBundleVersion": "codeql-bundle-v2.18.1",
-  "priorCliVersion": "2.18.1"
+  "bundleVersion": "codeql-bundle-v2.18.3",
+  "cliVersion": "2.18.3",
+  "priorBundleVersion": "codeql-bundle-v2.18.2",
+  "priorCliVersion": "2.18.2"
 }