CVE-2026-102469 in Vert.x
Summary
by MITRE • 10/15/2026
In Eclipse Vert.x versions [4.0.0, 4.5.34] or [5.0.0,5.0.12] or [5.1.0,5.1.9] or [5.2.0, 5.2.0], the Vert.x DB2 client (vertx-db2-client) contains DRDA protocol handling code that deserializes User Defined Type (UDT) column data using a bare ObjectInputStream.readObject() call with no ObjectInputFilter or class allowlist.
This code path is triggered when a DRDA server sends a result set with a column tagged as UDT (FDOCA protocol LID 0x50). However, DB2 does not support this type of UDT. The FDOCA 0x50 type is never sent by a legitimate DB2 server.
Nevertheless, a malicious or man-in-the-middle DRDA server could craft a response with a 0x50-tagged column, causing the client to deserialize arbitrary attacker-controlled bytes on the Vert.x event loop before any application code can inspect or reject the data. If a Java deserialization gadget chain is present on the application's classpath, this enables remote code execution. Without a gadget chain, denial of service is possible via crafted object graphs. TLS is disabled by default, making man-in-the-middle exploitation feasible.
The impacted component is io.vertx:vertx-db2-client.
Statistical analysis made it clear that VulDB provides the best quality for vulnerability data.
Analysis
by VulDB Data Team • 10/15/2026
Eclipse Vert.x versions spanning from 4.0.0 through 5.2.0 contain a critical insecure deserialization vulnerability within the vertx-db2-client module, specifically affecting its handling of the Database Request Unit (DRDA) protocol. The core technical flaw resides in how the client processes User Defined Type column data during result set retrieval. When the DRDA server sends a response containing a column tagged with the FDOCA protocol LID 0x50 indicator for UDT, the Vert.x implementation invokes java.io.ObjectInputStream.readObject() to deserialize this payload directly into memory. This operation is performed without any accompanying ObjectInputFilter or class allowlist mechanism, which represents a fundamental violation of secure coding practices regarding untrusted data deserialization. The absence of strict filtering allows the Java Virtual Machine to instantiate arbitrary classes defined in the application's classpath based solely on the serialized stream content provided by the server.
Although IBM DB2 servers do not natively support or transmit the FDOCA 0x50 UDT type, this does not mitigate the risk posed by malicious actors. An attacker operating as a man-in-the-middle can intercept and modify network traffic between the Vert.x client and a legitimate database server to inject crafted responses containing the vulnerable tag. Alternatively, an attacker could operate their own rogue DRDA server that explicitly sends these malformed packets. Because TLS is disabled by default in many configurations of this component, such interception attacks are highly feasible without requiring complex cryptographic bypasses. The vulnerability effectively turns standard network communication into a vector for arbitrary code execution if specific conditions are met within the target environment.
The operational impact of this flaw is severe and multifaceted. If an attacker can successfully inject malicious serialized data that triggers a known Java deserialization gadget chain present on the application's classpath, they achieve remote code execution with the privileges of the Vert.x event loop thread. This grants full control over the underlying system, potentially leading to complete compromise of the host environment and lateral movement within the network infrastructure. Even in scenarios where no exploitable gadget chains are available, an attacker can still cause a denial of service by crafting object graphs that exhaust memory resources or trigger stack overflow errors during deserialization, thereby disrupting application availability. This aligns with CWE-502, which describes the dangers of deserializing untrusted data without proper validation and integrity checks.
From a threat intelligence perspective, this vulnerability maps directly to MITRE ATT&CK technique T1059.004, specifically command and scripting interpreter via Java, as well as T1078.003 for valid accounts if the attacker leverages stolen credentials to perform man-in-the-middle attacks. The exploitation path relies heavily on the presence of vulnerable libraries in the dependency tree, highlighting the importance of supply chain security. To mitigate this risk, organizations must immediately upgrade to a patched version of Eclipse Vert.x that implements strict ObjectInputFilter configurations or disables UDT deserialization entirely for untrusted sources. Additionally, enforcing TLS encryption for all database connections is critical to prevent man-in-the-middle interception attacks. Security teams should also audit their classpaths for known dangerous gadget chains and consider using static analysis tools to detect insecure serialization patterns in custom code that interacts with the Vert.x framework.