diff --git a/spring-core/src/main/java/org/springframework/util/xml/AbstractXMLStreamReader.java b/spring-core/src/main/java/org/springframework/util/xml/AbstractXMLStreamReader.java
index 1c92c458fcd..1bba07dc5f3 100644
--- a/spring-core/src/main/java/org/springframework/util/xml/AbstractXMLStreamReader.java
+++ b/spring-core/src/main/java/org/springframework/util/xml/AbstractXMLStreamReader.java
@@ -190,7 +190,7 @@ abstract class AbstractXMLStreamReader implements XMLStreamReader {
 	@Override
 	public int getTextCharacters(int sourceStart, char[] target, int targetStart, int length) {
 		char[] source = getTextCharacters();
-		length = Math.min(length, source.length);
+		length = Math.min(length, source.length - sourceStart);
 		System.arraycopy(source, sourceStart, target, targetStart, length);
 		return length;
 	}
diff --git a/spring-core/src/main/java/org/springframework/util/xml/XMLEventStreamReader.java b/spring-core/src/main/java/org/springframework/util/xml/XMLEventStreamReader.java
index e554dbd6ebd..3e8725e3d76 100644
--- a/spring-core/src/main/java/org/springframework/util/xml/XMLEventStreamReader.java
+++ b/spring-core/src/main/java/org/springframework/util/xml/XMLEventStreamReader.java
@@ -34,9 +34,11 @@ import javax.xml.stream.events.XMLEvent;
 import org.jspecify.annotations.Nullable;
 
 /**
- * Implementation of the {@link javax.xml.stream.XMLStreamReader} interface that wraps a
- * {@link XMLEventReader}. Useful because the StAX {@link javax.xml.stream.XMLInputFactory}
- * allows one to create an event reader from a stream reader, but not vice-versa.
+ * Implementation of the {@link javax.xml.stream.XMLStreamReader} interface that wraps an
+ * {@link XMLEventReader}.
+ *
+ * <p>Useful because the StAX {@link javax.xml.stream.XMLInputFactory} allows one
+ * to create an event reader from a stream reader, but not vice-versa.
  *
  * @author Arjen Poutsma
  * @since 3.0
diff --git a/spring-core/src/test/java/org/springframework/util/xml/XMLEventStreamReaderTests.java b/spring-core/src/test/java/org/springframework/util/xml/XMLEventStreamReaderTests.java
index 40ef3b6410d..def40b8be90 100644
--- a/spring-core/src/test/java/org/springframework/util/xml/XMLEventStreamReaderTests.java
+++ b/spring-core/src/test/java/org/springframework/util/xml/XMLEventStreamReaderTests.java
@@ -21,13 +21,15 @@ import java.io.StringWriter;
 
 import javax.xml.stream.XMLEventReader;
 import javax.xml.stream.XMLInputFactory;
+import javax.xml.stream.XMLStreamConstants;
 import javax.xml.transform.Transformer;
 import javax.xml.transform.TransformerFactory;
 import javax.xml.transform.stax.StAXSource;
 import javax.xml.transform.stream.StreamResult;
 
-import org.junit.jupiter.api.BeforeEach;
 import org.junit.jupiter.api.Test;
+import org.junit.jupiter.params.ParameterizedTest;
+import org.junit.jupiter.params.provider.CsvSource;
 import org.w3c.dom.Node;
 import org.xmlunit.util.Predicate;
 
@@ -35,21 +37,24 @@ import org.springframework.core.testfixture.xml.XmlContent;
 
 import static org.assertj.core.api.Assertions.assertThat;
 
+/**
+ * Tests for {@link XMLEventStreamReader}.
+ */
 class XMLEventStreamReaderTests {
 
 	private static final String XML =
-			"<?pi content?><root xmlns='namespace'><prefix:child xmlns:prefix='namespace2'>content</prefix:child></root>"
-			;
+			"<?pi content?><root xmlns='namespace'><prefix:child xmlns:prefix='namespace2'>content</prefix:child></root>";
 
-	private XMLEventStreamReader streamReader;
+	private final XMLEventStreamReader streamReader;
 
-	@BeforeEach
-	void createStreamReader() throws Exception {
+
+	XMLEventStreamReaderTests() throws Exception {
 		XMLInputFactory inputFactory = XMLInputFactory.newInstance();
 		XMLEventReader eventReader = inputFactory.createXMLEventReader(new StringReader(XML));
-		streamReader = new XMLEventStreamReader(eventReader);
+		this.streamReader = new XMLEventStreamReader(eventReader);
 	}
 
+
 	@Test
 	void readAll() throws Exception {
 		while (streamReader.hasNext()) {
@@ -68,4 +73,30 @@ class XMLEventStreamReaderTests {
 		assertThat(XmlContent.from(writer)).isSimilarTo(XML, nodeFilter);
 	}
 
+	@ParameterizedTest  // gh-36914
+	@CsvSource(textBlock = """
+			0, content
+			1, ontent
+			4, ent
+			6, t
+			7, ''
+			""")
+	void getTextCharactersHonorsSourceStart(int sourceStart, String expected) throws Exception {
+		advanceToCharacters();
+
+		// text node is "content" (7 chars); request an oversized buffer to ensure
+		// getTextCharacters(sourceStart, ...) does not read past the source
+		char[] target = new char[10];
+		int count = streamReader.getTextCharacters(sourceStart, target, 0, 10);
+
+		assertThat(count).isEqualTo(expected.length());
+		assertThat(new String(target, 0, count)).isEqualTo(expected);
+	}
+
+	private void advanceToCharacters() throws Exception {
+		while (streamReader.getEventType() != XMLStreamConstants.CHARACTERS) {
+			streamReader.next();
+		}
+	}
+
 }