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CVE-2023-54398 – Unauthenticated RCE via Java Deserialization – Yonyou U8 Cloud 1.0–3.6sp

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Summary

CVE-2023-54398 is an unauthenticated Java deserialization vulnerability affecting Yonyou U8 Cloud, an enterprise resource planning (ERP) platform. The flaw resides in the FileManageServlet component and allows a remote, unauthenticated attacker to execute arbitrary operating system commands on the underlying server. Given the network attack vector, absence of authentication requirements, and full impact on confidentiality, integrity, and availability, this vulnerability is rated critical.

Technical details

  • Root cause: CWE-502 (Deserialization of Untrusted Data). The doAction method in FileManageServlet passes raw HTTP request body data directly into ObjectInputStream.readObject() without any filtering or validation of the serialized data.
  • Trigger conditions: An attacker sends a crafted POST request containing a malicious serialized Java object to the vulnerable servlet endpoint.
  • Attack vector: Network-based; no authentication and no user interaction are required to exploit the vulnerability.
  • Impact: Successful exploitation results in remote code execution, allowing an attacker to run arbitrary OS commands and fully compromise the affected server.
  • Exploitation activity: Active exploitation of this vulnerability in the wild has been documented, and it is tracked as a known exploited vulnerability.

Affected software

  • Yonyou U8 Cloud, versions: 1.0, 2.0, 2.1, 2.3, 2.5, 2.6, 2.65, 2.7, 3.0, 3.1, 3.2, 3.5, 3.6, 3.6sp

Severity

  • CVSS v4.0 Base Score: 9.3 (Critical)
  • Vector: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N
  • A related CVSS v3.1 scoring of 9.8 (Critical) has also been reported for this vulnerability (AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H).

Mitigation and recommended actions

  • Immediate: Apply the official fix published by Yonyou through its security advisory center. Organizations running any of the affected U8 Cloud versions listed above should consult and apply the vendor’s patch as soon as possible.
  • If immediate patching is not possible:
    • Restrict network access to U8 Cloud instances so they are not directly reachable from the public internet.
    • Place the application behind a web application firewall (WAF) or reverse proxy capable of inspecting and blocking anomalous POST requests to file-management endpoints.
    • Monitor server logs and network traffic for unexpected POST requests to file-management servlet paths and for anomalous outbound connections or process execution originating from the application server.
    • Given documented active exploitation, treat internet-facing U8 Cloud deployments as high priority for remediation.

References

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