Bound the memory usage when decompressing CompressedCertificate

src/java.base/share/classes/sun/security/ssl/CompressionAlgorithm.java

@@ -171,6 +171,22 @@ enum CompressionAlgorithm {
                 while (!inflater.finished()) {
                     int decompressedSize = inflater.inflate(buffer);
                     outputStream.write(buffer, 0, decompressedSize);
+
+                    // Bound the memory usage.
+                    if (outputStream.size()
+                            > SSLConfiguration.maxHandshakeMessageSize) {
+                        if (SSLLogger.isOn()
+                                && SSLLogger.isOn(SSLLogger.Opt.HANDSHAKE)) {
+                            SSLLogger.warning("The size of the "
+                                    + "uncompressed certificate message "
+                                    + "exceeds maximum allowed size of "
+                                    + SSLConfiguration.maxHandshakeMessageSize
+                                    + " bytes; compressed size: "
+                                    + input.length);
+                        }
+
+                        return null;
+                    }
                 }
 
                 return outputStream.toByteArray();

test/jdk/sun/security/ssl/CertificateCompression/BoundDecompressMemory.java

@@ -0,0 +1,86 @@
+/*
+ * Copyright (c) 2026, Oracle and/or its affiliates. All rights reserved.
+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
+ *
+ * This code is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 only, as
+ * published by the Free Software Foundation.
+ *
+ * This code is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ * version 2 for more details (a copy is included in the LICENSE file that
+ * accompanied this code).
+ *
+ * You should have received a copy of the GNU General Public License version
+ * 2 along with this work; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
+ * or visit www.oracle.com if you need additional information or have any
+ * questions.
+ */
+
+import static jdk.test.lib.Asserts.assertEquals;
+import static jdk.test.lib.Asserts.assertNotNull;
+import static jdk.test.lib.Asserts.assertTrue;
+import static jdk.test.lib.Utils.runAndCheckException;
+import static jdk.test.lib.security.SecurityUtils.runAndGetLog;
+
+import java.util.Scanner;
+import javax.net.ssl.SSLHandshakeException;
+
+/*
+ * @test
+ * @bug 8372526
+ * @summary Bound the memory usage when decompressing CompressedCertificate.
+ * @modules java.base/sun.security.x509
+ *          java.base/sun.security.util
+ * @library /javax/net/ssl/templates
+ *          /test/lib
+ * @run main/othervm BoundDecompressMemory
+ */
+
+public class BoundDecompressMemory extends CompressedCertMsgCache {
+
+    private static final int MAX_HANDSHAKE_MESSAGE_SIZE = 4096;
+
+    public static void main(String[] args) throws Exception {
+        System.setProperty("jdk.tls.maxHandshakeMessageSize",
+                Integer.toString(MAX_HANDSHAKE_MESSAGE_SIZE));
+
+        String log = runAndGetLog(() -> {
+            try {
+                // Use highly compressible subject name for server's certificate.
+                serverCertSubjectName = "O=Some-Org"
+                        + "A".repeat(MAX_HANDSHAKE_MESSAGE_SIZE)
+                        + ", L=Some-City, ST=Some-State, C=US";
+
+                setupCertificates();
+                serverSslContext = getSSLContext(trustedCert, serverCert,
+                        serverKeys.getPrivate(), "TLSv1.3");
+                clientSslContext = getSSLContext(trustedCert, clientCert,
+                        clientKeys.getPrivate(), "TLSv1.3");
+
+                runAndCheckException(() -> new BoundDecompressMemory().run(),
+                        serverEx -> {
+                            Throwable clientEx = serverEx.getSuppressed()[0];
+                            assertTrue(
+                                    clientEx instanceof SSLHandshakeException);
+                            assertEquals("(bad_certificate) Improper "
+                                            + "certificate compression",
+                                    clientEx.getMessage());
+                        }
+                );
+            } catch (Exception _) {
+            }
+        });
+
+        // Check for the specific decompression error message.
+        assertNotNull(new Scanner(log).findWithinHorizon("The size of the "
+                + "uncompressed certificate message "
+                + "exceeds maximum allowed size of "
+                + MAX_HANDSHAKE_MESSAGE_SIZE
+                + " bytes; compressed size: \\d+", 0));
+    }
+}

test/jdk/sun/security/ssl/CertificateCompression/CompressedCertMsgCache.java

@@ -57,13 +57,18 @@ import jdk.test.lib.security.CertificateBuilder;
 
 public class CompressedCertMsgCache extends SSLSocketTemplate {
 
-    private static X509Certificate trustedCert;
-    private static X509Certificate serverCert;
-    private static X509Certificate clientCert;
-    private static KeyPair serverKeys;
-    private static KeyPair clientKeys;
-    private static SSLContext serverSslContext;
-    private static SSLContext clientSslContext;
+    protected static String clientCertSubjectName =
+            "CN=localhost, OU=SSL-Client, ST=Some-State, C=US";
+    protected static String serverCertSubjectName =
+            "O=Some-Org, L=Some-City, ST=Some-State, C=US";
+
+    protected static X509Certificate trustedCert;
+    protected static X509Certificate serverCert;
+    protected static X509Certificate clientCert;
+    protected static KeyPair serverKeys;
+    protected static KeyPair clientKeys;
+    protected static SSLContext serverSslContext;
+    protected static SSLContext clientSslContext;
 
     public static void main(String[] args) throws Exception {
 
@@ -106,7 +111,7 @@ public class CompressedCertMsgCache extends SSLSocketTemplate {
         return clientSslContext;
     }
 
-    private static SSLContext getSSLContext(
+    protected static SSLContext getSSLContext(
             X509Certificate trustedCertificate, X509Certificate keyCertificate,
             PrivateKey privateKey, String protocol)
             throws Exception {
@@ -143,7 +148,7 @@ public class CompressedCertMsgCache extends SSLSocketTemplate {
 
     // Certificate-building helper methods.
 
-    private static void setupCertificates() throws Exception {
+    protected static void setupCertificates() throws Exception {
         KeyPairGenerator kpg = KeyPairGenerator.getInstance("EC");
         KeyPair caKeys = kpg.generateKeyPair();
         serverKeys = kpg.generateKeyPair();
@@ -152,13 +157,13 @@ public class CompressedCertMsgCache extends SSLSocketTemplate {
         trustedCert = createTrustedCert(caKeys);
 
         serverCert = customCertificateBuilder(
-                "O=Some-Org, L=Some-City, ST=Some-State, C=US",
+                serverCertSubjectName,
                 serverKeys.getPublic(), caKeys.getPublic())
                 .addBasicConstraintsExt(false, false, -1)
                 .build(trustedCert, caKeys.getPrivate(), "SHA256withECDSA");
 
         clientCert = customCertificateBuilder(
-                "CN=localhost, OU=SSL-Client, ST=Some-State, C=US",
+                clientCertSubjectName,
                 clientKeys.getPublic(), caKeys.getPublic())
                 .addBasicConstraintsExt(false, false, -1)
                 .build(trustedCert, caKeys.getPrivate(), "SHA256withECDSA");