Description

Deserialization of untrusted data in Azure Service Bus allows an authorized attacker to execute code over a network.

Executive Summary

Technical Details

Mitigations

References

Additional Metadata

{
  "score": "9.9",
  "pubDate": "2026-08-07T00:16:31.140Z",
  "pubdate": "2026-08-07T00:16:31.140Z",
  "executiveSummary": "A deserialization of untrusted data vulnerability exists within Azure Service Bus, enabling an authenticated remote attacker to achieve arbitrary remote code execution over a network.\nThe flaw stems from the insecure handling and processing of serialized objects by the affected product, which fails to properly sanitize or validate input data before instantiation.\nAn attacker with network access and authorization to interact with the service can craft malicious payloads encapsulating arbitrary gadget chains or executable routines.\nUpon transmission to the vulnerable endpoint, the system deserializes the malicious input, triggering unintended code execution within the context of the application process.\nThe risk implications are severe, potentially leading to total compromise of the affected host system, unauthorized data access, lateral movement within the network, and complete loss of confidentiality, integrity, and availability.\nExploitation requires network connectivity to the target service and valid authorization credentials, restricting the attack vector to authenticated entities within the operational environment.",
  "technicalDetails": "The vulnerability resides in the deserialization routines implemented within Azure Service Bus, specifically where input streams containing serialized object graphs are processed without adequate type restrictions or safe deserialization filters.\nThe root cause is the reliance on insecure native or framework-level serialization mechanisms that instantiate arbitrary types and invoke associated lifecycle methods or property setters during the reconstruction of objects from byte streams.\nAttackers exploit this behavior by identifying entry points that accept complex objects or serialized payloads. By leveraging publicly known gadget chains or constructing custom payloads tailored to the target runtime environment, the attacker encapsulates malicious execution sequences within the serialized data structure.\nThe attack flow proceeds as follows: First, the attacker establishes network connectivity to the vulnerable Azure Service Bus interface. Second, utilizing authorized access credentials, the attacker transmits a crafted request or message containing the malicious serialized payload to the vulnerable component.\nThird, the service receives the input and passes it to the internal deserialization handler. Fourth, the runtime environment reconstructs the object graph, automatically triggering the execution of embedded gadget chains or dangerous methods during or immediately after the deserialization process.\nThis sequence bypasses standard execution flow controls, resulting in arbitrary code execution on the underlying host operating system with the privileges of the service process.\nNetwork exposure is defined by the accessibility of the Azure Service Bus endpoints. Authentication and privilege requirements mandate that the attacker possesses valid credentials to interact with the service, meaning the threat model primarily addresses authenticated privilege escalation or lateral compromise by compromised insiders or external entities with breached credentials.\nPost-exploitation impact includes persistent system access, deployment of secondary payloads, privilege escalation, interception of sensitive messages, and disruption of messaging infrastructure operations."
}