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markt pushed a commit to branch main
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The following commit(s) were added to refs/heads/main by this push:
new 9de3e3e68f Fix an edge case HTTP/2 HPACK header decoding bug
9de3e3e68f is described below
commit 9de3e3e68f55a8a83a711af0dbc1bc6965ae7736
Author: Mark Thomas <[email protected]>
AuthorDate: Fri Apr 17 10:04:00 2026 +0100
Fix an edge case HTTP/2 HPACK header decoding bug
---
java/org/apache/coyote/http2/HPackHuffman.java | 5 +++
test/org/apache/coyote/http2/TestHPackHuffman.java | 45 ++++++++++++++++++++++
webapps/docs/changelog.xml | 5 +++
3 files changed, 55 insertions(+)
diff --git a/java/org/apache/coyote/http2/HPackHuffman.java
b/java/org/apache/coyote/http2/HPackHuffman.java
index 6ca431c3ae..726dbba9a5 100644
--- a/java/org/apache/coyote/http2/HPackHuffman.java
+++ b/java/org/apache/coyote/http2/HPackHuffman.java
@@ -387,11 +387,14 @@ public class HPackHuffman {
if ((val & LOW_TERMINAL_BIT) == 0) {
treePos = val & LOW_MASK;
eosBits = false;
+ // Found a zero, can't be counting EOS bits
eosBitCount = 0;
} else {
target.append((char) (val & LOW_MASK));
treePos = 0;
eosBits = true;
+ // Output a character, reset eosBitCount
+ eosBitCount = 0;
}
} else {
if (eosBits) {
@@ -409,6 +412,8 @@ public class HPackHuffman {
target.append((char) ((val >> 16) & LOW_MASK));
treePos = 0;
eosBits = true;
+ // Output a character, reset eosBitCount
+ eosBitCount = 0;
}
}
bitPos--;
diff --git a/test/org/apache/coyote/http2/TestHPackHuffman.java
b/test/org/apache/coyote/http2/TestHPackHuffman.java
new file mode 100644
index 0000000000..7b970d499b
--- /dev/null
+++ b/test/org/apache/coyote/http2/TestHPackHuffman.java
@@ -0,0 +1,45 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements. See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF licenses this file to You under the Apache License, Version 2.0
+ * (the "License"); you may not use this file except in compliance with
+ * the License. You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.apache.coyote.http2;
+
+import java.nio.ByteBuffer;
+
+import org.junit.Assert;
+import org.junit.Test;
+
+
+public class TestHPackHuffman {
+
+ /*
+ * This specific String exposed an edge case that triggered an unexpected
HPACK parsing failure.
+ */
+ @Test
+ public void testValueLeftBrace() throws Exception {
+ ByteBuffer buf = ByteBuffer.allocate(10);
+ String data = "x-value{";
+ HPackHuffman.encode(buf, data, false);
+
+ buf.flip();
+ // Remove the header byte (in Tomcat this is parsed before the bytes
are passed to the HPACK decoder)
+ buf.get();
+
+ StringBuilder target = new StringBuilder();
+ HPackHuffman.decode(buf, buf.remaining(), target);
+
+ Assert.assertEquals("Value changed after encode/decode roundtrip",
data, target.toString());
+ }
+}
diff --git a/webapps/docs/changelog.xml b/webapps/docs/changelog.xml
index 0ecbb5b9bc..4bb96366ef 100644
--- a/webapps/docs/changelog.xml
+++ b/webapps/docs/changelog.xml
@@ -241,6 +241,11 @@
<update>
Remove support for HTTP 0.9. (markt)
</update>
+ <fix>
+ Correct an unlikely edge-case parsing bug in the HTTP/2 HPACK header
+ decoding that could result in a valid header triggering an unexpected
+ connection close. (markt)
+ </fix>
<!-- Entries for backport and removal before 12.0.0-M1 below this line
-->
<fix>
Avoid various edge cases if <code>Content-Length</code> is set via
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