diff --git a/engines/base/src/main/java/org/alfresco/transform/base/fs/FileManager.java b/engines/base/src/main/java/org/alfresco/transform/base/fs/FileManager.java
index 38fafbd0..b950fe4c 100644
--- a/engines/base/src/main/java/org/alfresco/transform/base/fs/FileManager.java
+++ b/engines/base/src/main/java/org/alfresco/transform/base/fs/FileManager.java
@@ -43,7 +43,6 @@ import java.io.OutputStream;
 import java.net.MalformedURLException;
 import java.net.URI;
 import java.net.URISyntaxException;
-import java.net.URL;
 import java.nio.file.Files;
 import java.util.UUID;
 import jakarta.servlet.http.HttpServletRequest;
@@ -193,21 +192,23 @@ public class FileManager
     {
         try
         {
-            URL url = new URL(directUrl);
-            String protocol = url.getProtocol();
+            // Parse without re-encoding so pre-signed URL query strings (e.g. S3/Azure) are
+            // forwarded verbatim. The 7-arg URI constructor would percent-encode the query,
+            // turning '%' into '%25' and invalidating any pre-computed signature (ACS-12053).
+            URI uri = new URI(directUrl);
+            String protocol = uri.getScheme();
             if ("http".equalsIgnoreCase(protocol) || "https".equalsIgnoreCase(protocol))
             {
-                String host = url.getHost();
+                String host = uri.getHost();
                 if (host == null || !host.matches("[A-Za-z0-9._\\-]+"))
                 {
                     throw new TransformException(BAD_REQUEST, "Direct Access Url host is not allowed.");
                 }
-                return new URI(protocol, null, host, url.getPort(),
-                        url.getPath(), url.getQuery(), null).toURL().openStream();
+                return uri.toURL().openStream();
             }
             if ("file".equalsIgnoreCase(protocol))
             {
-                File localFile = assertWithinTempDir(new File(url.toURI()));
+                File localFile = assertWithinTempDir(new File(uri));
                 return Files.newInputStream(localFile.toPath());
             }
             throw new TransformException(BAD_REQUEST, "Direct Access Url protocol is not allowed.");
diff --git a/engines/base/src/test/java/org/alfresco/transform/base/fs/FileManagerTest.java b/engines/base/src/test/java/org/alfresco/transform/base/fs/FileManagerTest.java
new file mode 100644
index 00000000..75e7cbf5
--- /dev/null
+++ b/engines/base/src/test/java/org/alfresco/transform/base/fs/FileManagerTest.java
@@ -0,0 +1,126 @@
+/*
+ * #%L
+ * Alfresco Transform Core
+ * %%
+ * Copyright (C) 2005 - 2026 Alfresco Software Limited
+ * %%
+ * This file is part of the Alfresco software.
+ * -
+ * If the software was purchased under a paid Alfresco license, the terms of
+ * the paid license agreement will prevail.  Otherwise, the software is
+ * provided under the following open source license terms:
+ * -
+ * Alfresco is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Lesser General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ * -
+ * Alfresco 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 Lesser General Public License for more details.
+ * -
+ * You should have received a copy of the GNU Lesser General Public License
+ * along with Alfresco. If not, see <http://www.gnu.org/licenses/>.
+ * #L%
+ */
+package org.alfresco.transform.base.fs;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertThrows;
+
+import java.io.IOException;
+import java.io.InputStream;
+import java.net.InetSocketAddress;
+import java.nio.charset.StandardCharsets;
+import java.util.concurrent.atomic.AtomicReference;
+
+import com.sun.net.httpserver.HttpServer;
+import org.junit.jupiter.api.AfterEach;
+import org.junit.jupiter.api.BeforeEach;
+import org.junit.jupiter.api.Test;
+
+import org.alfresco.transform.exceptions.TransformException;
+
+/**
+ * Tests for {@link FileManager#getDirectAccessUrlInputStream(String)}.
+ * <p>
+ * In particular guards against ACS-12053 (double percent-encoding of the
+ * direct-access URL's query string), which broke S3/Azure pre-signed URLs
+ * because the rebuilt URL no longer matched the original signature.
+ */
+class FileManagerTest
+{
+    private HttpServer server;
+    private final AtomicReference<String> receivedRawQuery = new AtomicReference<>();
+    private final AtomicReference<String> receivedRawPath = new AtomicReference<>();
+    private int port;
+
+    @BeforeEach
+    void startServer() throws IOException
+    {
+        server = HttpServer.create(new InetSocketAddress("127.0.0.1", 0), 0);
+        server.createContext("/", exchange -> {
+            receivedRawPath.set(exchange.getRequestURI().getRawPath());
+            receivedRawQuery.set(exchange.getRequestURI().getRawQuery());
+            byte[] body = "ok".getBytes(StandardCharsets.UTF_8);
+            exchange.sendResponseHeaders(200, body.length);
+            try (var os = exchange.getResponseBody())
+            {
+                os.write(body);
+            }
+        });
+        server.start();
+        port = server.getAddress().getPort();
+    }
+
+    @AfterEach
+    void stopServer()
+    {
+        if (server != null)
+        {
+            server.stop(0);
+        }
+    }
+
+    /**
+     * Reproduces ACS-12053. A pre-signed S3-style URL with a query string that already contains
+     * percent-encoded characters must be forwarded verbatim; re-encoding the {@code %} sign
+     * invalidates the AWS signature and yields HTTP 400 from S3.
+     */
+    @Test
+    void preservesPercentEncodingInPreSignedUrlQuery() throws IOException
+    {
+        // Query taken from the ACS-12053 reproducer (truncated for the test).
+        // Contains pre-encoded characters: %3B (;), %20 (space), %3D (=), %22 ("), %2F (/).
+        String rawQuery = "response-content-disposition=attachment%3B%20filename%3D%22doc1.docx%22"
+                + "&X-Amz-Credential=AKIA%2F20260622%2Fus-east-2%2Fs3%2Faws4_request"
+                + "&X-Amz-Signature=deadbeef";
+        String url = "http://127.0.0.1:" + port + "/object.bin?" + rawQuery;
+
+        try (InputStream in = FileManager.getDirectAccessUrlInputStream(url))
+        {
+            in.readAllBytes();
+        }
+
+        assertEquals("/object.bin", receivedRawPath.get(),
+                "Path must be forwarded verbatim");
+        assertEquals(rawQuery, receivedRawQuery.get(),
+                "Query string must be forwarded verbatim without re-encoding the '%' sign (ACS-12053)");
+    }
+
+    @Test
+    void rejectsUnsupportedProtocol()
+    {
+        assertThrows(TransformException.class,
+                () -> FileManager.getDirectAccessUrlInputStream("ftp://example.com/file"));
+    }
+
+    @Test
+    void rejectsInvalidHost()
+    {
+        // host contains characters disallowed by the validator
+        assertThrows(TransformException.class,
+                () -> FileManager.getDirectAccessUrlInputStream("http://bad host/file"));
+    }
+}