CVE-2023-54398 in U8 Cloud
Summary
by MITRE • 09/15/2026
Yonyou U8 Cloud contains an unauthenticated Java deserialization vulnerability in the nc.impl.pub.filesystem.FileManageServlet component that allows remote unauthenticated attackers to execute arbitrary OS commands by sending a serialized payload via POST request. Attackers can exploit the doAction method, which passes raw HTTP request body data directly to ObjectInputStream.readObject() without filtering, to achieve remote code execution. Exploitation evidence was first observed by the Shadowserver Foundation on 2025-02-13.
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Analysis
by VulDB Data Team • 09/15/2026
The vulnerability identified in Yonyou U8 Cloud represents a critical security flaw rooted in insecure Java deserialization practices within the nc.impl.pub.filesystem.FileManageServlet component. This specific issue allows remote, unauthenticated attackers to execute arbitrary operating system commands on the affected server. The core of the problem lies in how the application handles incoming HTTP requests for file management operations. Specifically, the doAction method is designed to process raw data from the POST request body and passes it directly into java.io.ObjectInputStream.readObject() without any prior validation or filtering. In Java applications, deserialization involves reconstructing a previously serialized object from its byte stream representation. When this process occurs on untrusted input without proper safeguards, an attacker can craft a maliciously constructed serialized payload containing gadget chains that trigger arbitrary code execution during the reconstruction phase. This class of vulnerability is widely recognized in the cybersecurity community as CWE-502, which denotes Deserialization of Untrusted Data. The severity is amplified by the fact that no authentication is required to reach this endpoint, making it accessible to any internet-facing host running the vulnerable version of Yonyou U8 Cloud without needing valid credentials or prior access privileges.
The operational impact of exploiting this vulnerability is severe and immediate. Once an attacker successfully sends a crafted serialized payload via a POST request, the application will deserialize the data, triggering the embedded gadget chain within the Java runtime environment. This typically results in Remote Code Execution (RCE), granting the attacker full control over the underlying operating system processes running under the context of the Yonyou U8 Cloud service account. Depending on the configuration and permissions of that user, this could lead to complete compromise of the server, including data exfiltration, installation of persistent backdoors, pivoting into internal networks, or disruption of business-critical financial and enterprise resource planning functions managed by the software. The exploitation mechanism aligns with MITRE ATT&CK technique T1059, specifically Command and Scripting Interpreter sub-techniques such as T1059.004 for Unix Shell commands, as attackers often leverage this RCE to execute system-level commands directly on the host machine.
Evidence of active exploitation in the wild was first documented by the Shadowserver Foundation on February 13, 2025, indicating that threat actors are actively scanning and targeting vulnerable instances of Yonyou U8 Cloud over the internet. This real-world activity underscores the urgency for organizations to assess their exposure immediately. The lack of authentication requirements makes this vulnerability particularly attractive to automated botnets and opportunistic attackers who routinely scan public IP ranges for known deserialization flaws in enterprise software suites. Given that Yonyou is a prominent provider of ERP solutions, especially within Asian markets, successful exploitation could have significant financial and operational consequences for affected enterprises due to the sensitive nature of the data processed by these systems.
Mitigation strategies must focus on both immediate remediation and long-term architectural improvements. The most effective short-term solution is to apply vendor-provided patches or updates that address this specific deserialization flaw in the FileManageServlet component. If patching is not immediately feasible, organizations should implement network-level controls such as Web Application Firewalls (WAF) rules designed to detect and block common Java serialization markers or known malicious payload signatures associated with popular gadget chains like CommonsCollections or Spring AOP. Additionally, restricting access to the affected endpoint via IP whitelisting can reduce the attack surface by limiting exposure only to trusted internal networks rather than leaving it open to the public internet. From a development perspective, this incident highlights the necessity of avoiding direct deserialization of untrusted input entirely. Developers should adopt safer alternatives such as using JSON or XML with strict schema validation instead of Java native serialization for data exchange between clients and servers. Implementing allow-lists for expected object types during deserialization can also prevent arbitrary class instantiation that leads to code execution. Regular security assessments, including static application security testing (SAST) focused on insecure deserialization patterns, are essential to identify similar vulnerabilities before they reach production environments.