diff --git a/CHANGELOG.md b/CHANGELOG.md
index 267b4e557e..a8880f37aa 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 [2.27.1](https://github.com/github/codeql-action/releases/tag/codeql-bundle-v2.27.1). [#4160](https://github.com/github/codeql-action/pull/4160)
 
 ## 4.38.1 - 18 Sept 2026
 
diff --git a/lib/defaults.json b/lib/defaults.json
index e4875a8a34..e201dfd79e 100644
--- a/lib/defaults.json
+++ b/lib/defaults.json
@@ -1,6 +1,6 @@
 {
-  "bundleVersion": "codeql-bundle-v2.27.0",
-  "cliVersion": "2.27.0",
-  "priorBundleVersion": "codeql-bundle-v2.26.4",
-  "priorCliVersion": "2.26.4"
+  "bundleVersion": "codeql-bundle-v2.27.1",
+  "cliVersion": "2.27.1",
+  "priorBundleVersion": "codeql-bundle-v2.27.0",
+  "priorCliVersion": "2.27.0"
 }
diff --git a/lib/entry-points.js b/lib/entry-points.js
index 3fbacc32e4..2340dc38e6 100644
--- a/lib/entry-points.js
+++ b/lib/entry-points.js
@@ -147732,8 +147732,8 @@ var path6 = __toESM(require("path"));
 var semver4 = __toESM(require_semver2());
 
 // src/defaults.json
-var bundleVersion = "codeql-bundle-v2.27.0";
-var cliVersion = "2.27.0";
+var bundleVersion = "codeql-bundle-v2.27.1";
+var cliVersion = "2.27.1";
 
 // src/overlay/index.ts
 var fs5 = __toESM(require("fs"));
diff --git a/src/defaults.json b/src/defaults.json
index e4875a8a34..e201dfd79e 100644
--- a/src/defaults.json
+++ b/src/defaults.json
@@ -1,6 +1,6 @@
 {
-  "bundleVersion": "codeql-bundle-v2.27.0",
-  "cliVersion": "2.27.0",
-  "priorBundleVersion": "codeql-bundle-v2.26.4",
-  "priorCliVersion": "2.26.4"
+  "bundleVersion": "codeql-bundle-v2.27.1",
+  "cliVersion": "2.27.1",
+  "priorBundleVersion": "codeql-bundle-v2.27.0",
+  "priorCliVersion": "2.27.0"
 }