diff --git a/common/uri/src/main/java/io/helidon/common/uri/UriValidationException.java b/common/uri/src/main/java/io/helidon/common/uri/UriValidationException.java
index 8393d91297d..bed5a48286a 100644
--- a/common/uri/src/main/java/io/helidon/common/uri/UriValidationException.java
+++ b/common/uri/src/main/java/io/helidon/common/uri/UriValidationException.java
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2024 Oracle and/or its affiliates.
+ * Copyright (c) 2024, 2025 Oracle and/or its affiliates.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -38,6 +38,10 @@ public class UriValidationException extends IllegalArgumentException {
      * The value (containing illegal characters) that failed validation.
      */
     private final char[] invalidValue;
+    /**
+     * The index of the invalid char.
+     */
+    private final int index;
 
     /**
      * Create a new validation exception that uses a descriptive message and the failed chars.
@@ -52,6 +56,7 @@ public UriValidationException(Segment segment, char[] invalidValue, String messa
 
         this.segment = segment;
         this.invalidValue = invalidValue;
+        this.index = -1;
     }
 
     /**
@@ -67,6 +72,7 @@ public UriValidationException(Segment segment, char[] invalidValue, String messa
 
         this.segment = segment;
         this.invalidValue = invalidValue;
+        this.index = -1;
     }
 
     /**
@@ -84,6 +90,7 @@ public UriValidationException(Segment segment, char[] invalidValue, String messa
 
         this.segment = segment;
         this.invalidValue = invalidValue;
+        this.index = index;
     }
 
     /**
@@ -100,6 +107,7 @@ public UriValidationException(Segment segment, char[] invalidValue, String messa
 
         this.segment = segment;
         this.invalidValue = invalidValue;
+        this.index = index;
     }
 
     /**
@@ -121,6 +129,16 @@ public Segment segment() {
         return segment;
     }
 
+    /**
+     * Returns a safe message that does not include any user input and can be returned
+     * as part of a response.
+     *
+     * @return a safe message
+     */
+    public String safeMessage() {
+        return segment.text() + " contains invalid char" + (index != -1 ? " at index " + index : "");
+    }
+
     private static String toMessage(char[] value, String message) {
         Objects.requireNonNull(value);
         Objects.requireNonNull(message);
diff --git a/webserver/tests/webserver/src/test/java/io/helidon/webserver/tests/BadPrologueTest.java b/webserver/tests/webserver/src/test/java/io/helidon/webserver/tests/BadPrologueTest.java
index 80b83a712b0..063b6cdb187 100644
--- a/webserver/tests/webserver/src/test/java/io/helidon/webserver/tests/BadPrologueTest.java
+++ b/webserver/tests/webserver/src/test/java/io/helidon/webserver/tests/BadPrologueTest.java
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2024 Oracle and/or its affiliates.
+ * Copyright (c) 2024, 2025 Oracle and/or its affiliates.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -76,9 +76,8 @@ void testBadQuery() {
 
         assertThat(response, containsString("400 Bad Request"));
         // beginning of message to the first double quote
-        assertThat(response, containsString("Query contains invalid char: "));
+        assertThat(response, containsString("Query contains invalid char at index 2"));
         // end of message from double quote, index of bad char, and bad char
-        assertThat(response, containsString(", index: 2, char: 0x3c"));
         assertThat(response, not(containsString(">")));
     }
 
@@ -91,9 +90,8 @@ void testBadQueryCurly() {
 
         assertThat(response, containsString("400 Bad Request"));
         // beginning of message to the first double quote
-        assertThat(response, containsString("Query contains invalid char: "));
+        assertThat(response, containsString("Query contains invalid char at index 10"));
         // end of message from double quote, index of bad char, and bad char
-        assertThat(response, containsString(", index: 10, char: 0x7b"));
     }
 
     @Test
@@ -117,9 +115,8 @@ void testBadFragment() {
 
         assertThat(response, containsString("400 Bad Request"));
         // beginning of message to the first double quote
-        assertThat(response, containsString("Fragment contains invalid char: "));
+        assertThat(response, containsString("Fragment contains invalid char at index 16"));
         // end of message from double quote, index of bad char, and bad char
-        assertThat(response, containsString(", index: 16, char: 0x3e"));
         assertThat(response, not(containsString(">")));
     }
 }
diff --git a/webserver/webserver/src/main/java/io/helidon/webserver/http1/Http1Connection.java b/webserver/webserver/src/main/java/io/helidon/webserver/http1/Http1Connection.java
index acc07c4c963..33872b2f3ee 100644
--- a/webserver/webserver/src/main/java/io/helidon/webserver/http1/Http1Connection.java
+++ b/webserver/webserver/src/main/java/io/helidon/webserver/http1/Http1Connection.java
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2022, 2024 Oracle and/or its affiliates.
+ * Copyright (c) 2022, 2025 Oracle and/or its affiliates.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -37,6 +37,7 @@
 import io.helidon.common.mapper.MapperException;
 import io.helidon.common.task.InterruptableTask;
 import io.helidon.common.tls.TlsUtils;
+import io.helidon.common.uri.UriValidationException;
 import io.helidon.common.uri.UriValidator;
 import io.helidon.http.BadRequestException;
 import io.helidon.http.DateTime;
@@ -335,7 +336,7 @@ private void validatePrologue(HttpPrologue prologue) {
                     .status(Status.BAD_REQUEST_400)
                     .request(DirectTransportRequest.create(prologue, ServerRequestHeaders.create()))
                     .setKeepAlive(false)
-                    .message(e.getMessage())
+                    .message(e instanceof UriValidationException ve ? ve.safeMessage() : e.getMessage())
                     .safeMessage(true)
                     .cause(e)
                     .build();