diff --git a/.github/workflows/codeql-analysis.yml b/.github/workflows/codeql-analysis.yml
index fa17f4d6742d..acd0cedabcd1 100644
--- a/.github/workflows/codeql-analysis.yml
+++ b/.github/workflows/codeql-analysis.yml
@@ -28,7 +28,7 @@ jobs:
 
     steps:
     - name: Setup dotnet
-      uses: actions/setup-dotnet@v2
+      uses: actions/setup-dotnet@v3
       with:
         dotnet-version: 6.0.202
 
diff --git a/java/ql/lib/change-notes/2022-09-22-stringjoiner-summaries.md b/java/ql/lib/change-notes/2022-09-22-stringjoiner-summaries.md
new file mode 100644
index 000000000000..d1784d013f61
--- /dev/null
+++ b/java/ql/lib/change-notes/2022-09-22-stringjoiner-summaries.md
@@ -0,0 +1,4 @@
+---
+category: minorAnalysis
+---
+* Added new flow steps for `java.util.StringJoiner`.
diff --git a/java/ql/lib/semmle/code/java/frameworks/Strings.qll b/java/ql/lib/semmle/code/java/frameworks/Strings.qll
index c09b959254dd..f913f941df1c 100644
--- a/java/ql/lib/semmle/code/java/frameworks/Strings.qll
+++ b/java/ql/lib/semmle/code/java/frameworks/Strings.qll
@@ -64,7 +64,15 @@ private class StringSummaryCsv extends SummaryModelCsv {
         "java.lang;StringBuilder;true;StringBuilder;;;Argument[0];Argument[-1];taint;manual",
         "java.lang;CharSequence;true;charAt;;;Argument[-1];ReturnValue;taint;manual",
         "java.lang;CharSequence;true;subSequence;;;Argument[-1];ReturnValue;taint;manual",
-        "java.lang;CharSequence;true;toString;;;Argument[-1];ReturnValue;taint;manual"
+        "java.lang;CharSequence;true;toString;;;Argument[-1];ReturnValue;taint;manual",
+        "java.util;StringJoiner;false;StringJoiner;;;Argument[0..2];Argument[-1];taint;manual",
+        "java.util;StringJoiner;false;add;;;Argument[0];Argument[-1];taint;manual",
+        "java.util;StringJoiner;false;add;;;Argument[-1];ReturnValue;value;manual",
+        "java.util;StringJoiner;false;merge;;;Argument[0];Argument[-1];taint;manual",
+        "java.util;StringJoiner;false;merge;;;Argument[-1];ReturnValue;value;manual",
+        "java.util;StringJoiner;false;setEmptyValue;;;Argument[0];Argument[-1];taint;manual",
+        "java.util;StringJoiner;false;setEmptyValue;;;Argument[-1];ReturnValue;value;manual",
+        "java.util;StringJoiner;false;toString;;;Argument[-1];ReturnValue;taint;manual",
       ]
   }
 }
diff --git a/java/ql/test/library-tests/dataflow/taint/StringJoinerTests.java b/java/ql/test/library-tests/dataflow/taint/StringJoinerTests.java
new file mode 100644
index 000000000000..a44fe56ca2e5
--- /dev/null
+++ b/java/ql/test/library-tests/dataflow/taint/StringJoinerTests.java
@@ -0,0 +1,92 @@
+import java.util.StringJoiner;
+
+public class StringJoinerTests {
+
+	Object taint() {
+		return null;
+	}
+
+	void sink(Object o) {}
+
+	public void test() throws Exception {
+		{
+			// "java.util;StringJoiner;false;StringJoiner;(CharSequence);;Argument[0];Argument[-1];taint;manual"
+			StringJoiner out = null;
+			CharSequence in = (CharSequence) taint();
+			out = new StringJoiner(in);
+			sink(out);
+		}
+		{
+			// "java.util;StringJoiner;false;StringJoiner;(CharSequence,CharSequence,CharSequence);;Argument[0];Argument[-1];taint;manual"
+			StringJoiner out = null;
+			CharSequence in = (CharSequence) taint();
+			out = new StringJoiner(in, null, null);
+			sink(out);
+		}
+		{
+			// "java.util;StringJoiner;false;StringJoiner;(CharSequence,CharSequence,CharSequence);;Argument[1];Argument[-1];taint;manual"
+			StringJoiner out = null;
+			CharSequence in = (CharSequence) taint();
+			out = new StringJoiner(null, in, null);
+			sink(out);
+		}
+		{
+			// "java.util;StringJoiner;false;StringJoiner;(CharSequence,CharSequence,CharSequence);;Argument[2];Argument[-1];taint;manual"
+			StringJoiner out = null;
+			CharSequence in = (CharSequence) taint();
+			out = new StringJoiner(null, null, in);
+			sink(out);
+		}
+		{
+			// "java.util;StringJoiner;false;add;;;Argument[-1];ReturnValue;value;manual"
+			StringJoiner out = null;
+			StringJoiner in = (StringJoiner) taint();
+			out = in.add(null);
+			sink(out);
+		}
+		{
+			// "java.util;StringJoiner;false;add;;;Argument[0];Argument[-1];taint;manual"
+			StringJoiner out = null;
+			CharSequence in = (CharSequence) taint();
+			out.add(in);
+			sink(out);
+		}
+		{
+			// "java.util;StringJoiner;false;merge;;;Argument[-1];ReturnValue;value;manual"
+			StringJoiner out = null;
+			StringJoiner in = (StringJoiner) taint();
+			out = in.merge(null);
+			sink(out);
+		}
+		{
+			// "java.util;StringJoiner;false;merge;;;Argument[0];Argument[-1];taint;manual"
+			StringJoiner out = null;
+			StringJoiner in = (StringJoiner) taint();
+			out.merge(in);
+			sink(out);
+		}
+		{
+			// "java.util;StringJoiner;false;setEmptyValue;;;Argument[-1];ReturnValue;taint;manual"
+			StringJoiner out = null;
+			StringJoiner in = (StringJoiner) taint();
+			out = in.setEmptyValue(null);
+			sink(out);
+		}
+		{
+			// "java.util;StringJoiner;false;setEmptyValue;;;Argument[0];Argument[-1];taint;manual"
+			StringJoiner out = null;
+			CharSequence in = (CharSequence) taint();
+			out.setEmptyValue(in);
+			sink(out);
+		}
+		{
+			// "java.util;StringJoiner;false;toString;;;Argument[-1];ReturnValue;taint;manual"
+			String out = null;
+			StringJoiner in = (StringJoiner) taint();
+			out = in.toString();
+			sink(out);
+		}
+
+	}
+
+}
diff --git a/java/ql/test/library-tests/dataflow/taint/test.expected b/java/ql/test/library-tests/dataflow/taint/test.expected
index 8b7d85321b4a..555dbb023b78 100644
--- a/java/ql/test/library-tests/dataflow/taint/test.expected
+++ b/java/ql/test/library-tests/dataflow/taint/test.expected
@@ -72,6 +72,17 @@
 | StringBuilderTests.java:70:15:70:21 | taint(...) | StringBuilderTests.java:73:10:73:26 | new String(...) |
 | StringBuilderTests.java:79:15:79:21 | taint(...) | StringBuilderTests.java:80:10:80:40 | toString(...) |
 | StringBuilderTests.java:86:15:86:21 | taint(...) | StringBuilderTests.java:87:10:87:27 | substring(...) |
+| StringJoinerTests.java:15:37:15:43 | taint(...) | StringJoinerTests.java:17:9:17:11 | out |
+| StringJoinerTests.java:22:37:22:43 | taint(...) | StringJoinerTests.java:24:9:24:11 | out |
+| StringJoinerTests.java:29:37:29:43 | taint(...) | StringJoinerTests.java:31:9:31:11 | out |
+| StringJoinerTests.java:36:37:36:43 | taint(...) | StringJoinerTests.java:38:9:38:11 | out |
+| StringJoinerTests.java:43:37:43:43 | taint(...) | StringJoinerTests.java:45:9:45:11 | out |
+| StringJoinerTests.java:50:37:50:43 | taint(...) | StringJoinerTests.java:52:9:52:11 | out |
+| StringJoinerTests.java:57:37:57:43 | taint(...) | StringJoinerTests.java:59:9:59:11 | out |
+| StringJoinerTests.java:64:37:64:43 | taint(...) | StringJoinerTests.java:66:9:66:11 | out |
+| StringJoinerTests.java:71:37:71:43 | taint(...) | StringJoinerTests.java:73:9:73:11 | out |
+| StringJoinerTests.java:78:37:78:43 | taint(...) | StringJoinerTests.java:80:9:80:11 | out |
+| StringJoinerTests.java:85:37:85:43 | taint(...) | StringJoinerTests.java:87:9:87:11 | out |
 | Varargs.java:7:8:7:14 | taint(...) | Varargs.java:14:10:14:10 | s |
 | Varargs.java:8:8:8:14 | taint(...) | Varargs.java:19:10:19:10 | s |
 | Varargs.java:8:17:8:23 | taint(...) | Varargs.java:19:10:19:10 | s |