diff --git a/CHANGELOG.md b/CHANGELOG.md
index bd770ab5f4..1ed123883f 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -4,7 +4,7 @@ See the [releases page](https://github.com/github/codeql-action/releases) for th
 
 ## [UNRELEASED]
 
-No user facing changes.
+- Update default CodeQL bundle version to [2.26.3](https://github.com/github/codeql-action/releases/tag/codeql-bundle-v2.26.3). [#4085](https://github.com/github/codeql-action/pull/4085)
 
 ## 4.37.6 - 04 Aug 2026
 
diff --git a/lib/defaults.json b/lib/defaults.json
index 558dce6e24..b5d9f13644 100644
--- a/lib/defaults.json
+++ b/lib/defaults.json
@@ -1,6 +1,6 @@
 {
-  "bundleVersion": "codeql-bundle-v2.26.2",
-  "cliVersion": "2.26.2",
-  "priorBundleVersion": "codeql-bundle-v2.26.1",
-  "priorCliVersion": "2.26.1"
+  "bundleVersion": "codeql-bundle-v2.26.3",
+  "cliVersion": "2.26.3",
+  "priorBundleVersion": "codeql-bundle-v2.26.2",
+  "priorCliVersion": "2.26.2"
 }
diff --git a/lib/entry-points.js b/lib/entry-points.js
index 92b1ff3ead..9ae4f875aa 100644
--- a/lib/entry-points.js
+++ b/lib/entry-points.js
@@ -147085,8 +147085,8 @@ var path5 = __toESM(require("path"));
 var semver4 = __toESM(require_semver2());
 
 // src/defaults.json
-var bundleVersion = "codeql-bundle-v2.26.2";
-var cliVersion = "2.26.2";
+var bundleVersion = "codeql-bundle-v2.26.3";
+var cliVersion = "2.26.3";
 
 // src/overlay/index.ts
 var fs4 = __toESM(require("fs"));
diff --git a/src/defaults.json b/src/defaults.json
index 558dce6e24..b5d9f13644 100644
--- a/src/defaults.json
+++ b/src/defaults.json
@@ -1,6 +1,6 @@
 {
-  "bundleVersion": "codeql-bundle-v2.26.2",
-  "cliVersion": "2.26.2",
-  "priorBundleVersion": "codeql-bundle-v2.26.1",
-  "priorCliVersion": "2.26.1"
+  "bundleVersion": "codeql-bundle-v2.26.3",
+  "cliVersion": "2.26.3",
+  "priorBundleVersion": "codeql-bundle-v2.26.2",
+  "priorCliVersion": "2.26.2"
 }