diff --git a/java/org/apache/tomcat/util/http/ConcurrentDateFormat.java b/java/org/apache/tomcat/util/http/ConcurrentDateFormat.java
index ce38872686fc..9fbb5df4ab7e 100644
--- a/java/org/apache/tomcat/util/http/ConcurrentDateFormat.java
+++ b/java/org/apache/tomcat/util/http/ConcurrentDateFormat.java
@@ -28,7 +28,7 @@
  * A thread safe wrapper around {@link SimpleDateFormat} that does not make use of ThreadLocal and - broadly - only
  * creates enough SimpleDateFormat objects to satisfy the concurrency requirements.
  */
-public class ConcurrentDateFormat {
+public class ConcurrentDateFormat implements FastHttpDateFormat.TryParseDateToTimestamp {
 
     private final String format;
     private final Locale locale;
@@ -88,6 +88,15 @@ public Date parse(String source) throws ParseException {
         }
     }
 
+    @Override
+    public long tryParseDate(String dateString) {
+        try {
+            return parse(dateString).getTime();
+        } catch (ParseException e) {
+            return -1;
+        }
+    }
+
     private SimpleDateFormat createInstance() {
         SimpleDateFormat sdf = new SimpleDateFormat(format, locale);
         sdf.setTimeZone(timezone);
diff --git a/java/org/apache/tomcat/util/http/FastHttpDateFormat.java b/java/org/apache/tomcat/util/http/FastHttpDateFormat.java
index 3abf32b67d30..f747c600887e 100644
--- a/java/org/apache/tomcat/util/http/FastHttpDateFormat.java
+++ b/java/org/apache/tomcat/util/http/FastHttpDateFormat.java
@@ -50,8 +50,9 @@ private FastHttpDateFormat() {
     private static final ConcurrentDateFormat FORMAT_RFC5322;
     private static final ConcurrentDateFormat FORMAT_OBSOLETE_RFC850;
     private static final ConcurrentDateFormat FORMAT_OBSOLETE_ASCTIME;
+    private static final TryParseDateToTimestamp FORMAT_RFC9651;
 
-    private static final ConcurrentDateFormat[] httpParseFormats;
+    private static final TryParseDateToTimestamp[] httpParseFormats;
 
     static {
         // All the formats that use a timezone use GMT
@@ -60,9 +61,20 @@ private FastHttpDateFormat() {
         FORMAT_RFC5322 = new ConcurrentDateFormat(DATE_RFC5322, Locale.US, tz);
         FORMAT_OBSOLETE_RFC850 = new ConcurrentDateFormat(DATE_OBSOLETE_RFC850, Locale.US, tz);
         FORMAT_OBSOLETE_ASCTIME = new ConcurrentDateFormat(DATE_OBSOLETE_ASCTIME, Locale.US, tz);
+        FORMAT_RFC9651 = dateString -> {
+            if(dateString == null || !dateString.startsWith("@")) {
+                return -1;
+            }
+            try {
+                // An RFC 9651 timestamp is in seconds, not milliseconds.
+                return Long.parseLong(dateString.substring(1)) * 1_000;
+            } catch (NumberFormatException e) {
+                return -1;
+            }
+        };
 
         httpParseFormats =
-                new ConcurrentDateFormat[] { FORMAT_RFC5322, FORMAT_OBSOLETE_RFC850, FORMAT_OBSOLETE_ASCTIME };
+                new TryParseDateToTimestamp[] { FORMAT_RFC5322, FORMAT_OBSOLETE_RFC850, FORMAT_OBSOLETE_ASCTIME, FORMAT_RFC9651 };
     }
 
     /**
@@ -146,13 +158,9 @@ public static long parseDate(String value) {
 
         long date = -1;
         for (int i = 0; (date == -1) && (i < httpParseFormats.length); i++) {
-            try {
-                date = httpParseFormats[i].parse(value).getTime();
-                updateParseCache(value, Long.valueOf(date));
-            } catch (ParseException e) {
-                // Ignore
-            }
+            date = httpParseFormats[i].tryParseDate(value);
         }
+        updateParseCache(value, Long.valueOf(date));
 
         return date;
     }
@@ -185,5 +193,14 @@ private static void updateParseCache(String key, Long value) {
         parseCache.put(key, value);
     }
 
-
+    @FunctionalInterface
+    interface TryParseDateToTimestamp {
+        /**
+         * Tries to parse the given string as a date and returns it as a timestamp.
+         *
+         * @param dateString the string representation of the date trying to be parsed
+         * @return the number of *milli*seconds since January 1, 1970, 00:00:00 GMT or -1 if parsing failed
+         */
+        long tryParseDate(String dateString);
+    }
 }
diff --git a/test/org/apache/tomcat/util/http/TestFastHttpDateFormat.java b/test/org/apache/tomcat/util/http/TestFastHttpDateFormat.java
index 20e771ef1ea9..395405f63457 100644
--- a/test/org/apache/tomcat/util/http/TestFastHttpDateFormat.java
+++ b/test/org/apache/tomcat/util/http/TestFastHttpDateFormat.java
@@ -1,3 +1,4 @@
+
 /*
  * Licensed to the Apache Software Foundation (ASF) under one or more
  * contributor license agreements.  See the NOTICE file distributed with
@@ -72,4 +73,25 @@ public void testGetCurrentDate() {
             Assert.assertTrue("Saw [" + changes + "] changes in formatted date", changes > 1 && changes < 5);
         }
     }
+
+    @Test
+    public void testRfc9651Date_valid() {
+        Assert.assertEquals(0L, FastHttpDateFormat.parseDate("@0"));
+        Assert.assertEquals(1000L, FastHttpDateFormat.parseDate("@1"));
+        Assert.assertEquals(-1000L, FastHttpDateFormat.parseDate("@-1"));
+        Assert.assertEquals(1659578233000L, FastHttpDateFormat.parseDate("@1659578233")); // Example from RFC
+        Assert.assertEquals(-62135596800000L, FastHttpDateFormat.parseDate("@-62135596800")); // Example from RFC
+        Assert.assertEquals(253402214400000L, FastHttpDateFormat.parseDate("@253402214400")); // Example from RFC
+    }
+
+    @Test
+    public void testRfc9651Date_invalid() {
+        Assert.assertEquals(-1L, FastHttpDateFormat.parseDate("@"));
+        Assert.assertEquals(-1L, FastHttpDateFormat.parseDate(" @1"));
+        Assert.assertEquals(-1L, FastHttpDateFormat.parseDate("@ 1"));
+        Assert.assertEquals(-1L, FastHttpDateFormat.parseDate("@0000-"));
+        Assert.assertEquals(-1L, FastHttpDateFormat.parseDate("@15+"));
+        Assert.assertEquals(-1L, FastHttpDateFormat.parseDate("@12p"));
+        Assert.assertEquals(-1L, FastHttpDateFormat.parseDate("@0x15"));
+    }
 }