diff --git a/README.md b/README.md
index 8c4fc46631..d738adcab6 100644
--- a/README.md
+++ b/README.md
@@ -76,7 +76,6 @@ We typically release new minor versions of the CodeQL Action and Bundle when a n
 | `v4.33.0` | `2.24.3` | Enterprise Server 3.21 | |
 | `v4.31.10` | `2.23.9` | Enterprise Server 3.20 | |
 | `v3.29.11` | `2.22.4` | Enterprise Server 3.19 | |
-| `v3.28.21` | `2.21.3` | Enterprise Server 3.18 | |
 
 See the full list of GHES release and deprecation dates at [GitHub Enterprise Server releases](https://docs.github.com/en/enterprise-server/admin/all-releases#releases-of-github-enterprise-server).
 
diff --git a/lib/entry-points.js b/lib/entry-points.js
index 7cea6c0b6d..196ca5584f 100644
--- a/lib/entry-points.js
+++ b/lib/entry-points.js
@@ -169371,7 +169371,7 @@ var semver = __toESM(require_semver2());
 
 // src/api-compatibility.json
 var maximumVersion = "3.23";
-var minimumVersion = "3.18";
+var minimumVersion = "3.19";
 
 // src/json/index.ts
 function parseString(data) {
@@ -176948,9 +176948,9 @@ async function getCombinedTracerConfig(logger2, codeql, config) {
 // src/codeql.ts
 var cachedCodeQL = void 0;
 var CODEQL_MINIMUM_VERSION = "2.20.7";
-var CODEQL_NEXT_MINIMUM_VERSION = "2.21.3";
-var GHES_VERSION_MOST_RECENTLY_DEPRECATED = "3.17";
-var GHES_MOST_RECENT_DEPRECATION_DATE = "2026-09-24";
+var CODEQL_NEXT_MINIMUM_VERSION = "2.22.4";
+var GHES_VERSION_MOST_RECENTLY_DEPRECATED = "3.18";
+var GHES_MOST_RECENT_DEPRECATION_DATE = "2026-10-16";
 var EXTRACTION_DEBUG_MODE_VERBOSITY = "progress++";
 function isDiskConfigurationError(e) {
   if (!(e instanceof Error)) {
diff --git a/src/api-compatibility.json b/src/api-compatibility.json
index c1122fb2a9..83ff180db0 100644
--- a/src/api-compatibility.json
+++ b/src/api-compatibility.json
@@ -1 +1 @@
-{"maximumVersion":"3.23","minimumVersion":"3.18"}
+{"maximumVersion":"3.23","minimumVersion":"3.19"}
diff --git a/src/codeql.ts b/src/codeql.ts
index 28ba2243e9..c1a8f4f340 100644
--- a/src/codeql.ts
+++ b/src/codeql.ts
@@ -260,17 +260,17 @@ const CODEQL_MINIMUM_VERSION = "2.20.7";
 /**
  * This version will shortly become the oldest version of CodeQL that the Action will run with.
  */
-const CODEQL_NEXT_MINIMUM_VERSION = "2.21.3";
+const CODEQL_NEXT_MINIMUM_VERSION = "2.22.4";
 
 /**
  * This is the version of GHES that was most recently deprecated.
  */
-const GHES_VERSION_MOST_RECENTLY_DEPRECATED = "3.17";
+const GHES_VERSION_MOST_RECENTLY_DEPRECATED = "3.18";
 
 /**
  * This is the deprecation date for the version of GHES that was most recently deprecated.
  */
-const GHES_MOST_RECENT_DEPRECATION_DATE = "2026-09-24";
+const GHES_MOST_RECENT_DEPRECATION_DATE = "2026-10-16";
 
 /** The CLI verbosity level to use for extraction in debug mode. */
 const EXTRACTION_DEBUG_MODE_VERBOSITY = "progress++";
diff --git a/unreleased-change-notes/ghes-3-18-deprecation.md b/unreleased-change-notes/ghes-3-18-deprecation.md
new file mode 100644
index 0000000000..0e33d39327
--- /dev/null
+++ b/unreleased-change-notes/ghes-3-18-deprecation.md
@@ -0,0 +1 @@
+- _Upcoming breaking change_: CodeQL version 2.22.3 and earlier were discontinued on 16 October 2026 alongside GitHub Enterprise Server 3.18, and will be unsupported by the next minor release of the CodeQL Action. Added a deprecation warning for customers using these versions of CodeQL. [#4266](https://github.com/github/codeql-action/pull/4266)