CVE-2026-115813 in Multi Model Server
Summary
by MITRE • 10/23/2026
Server-side request forgery in the model download path in Amazon Web Services Multi Model Server 1.1.11 and earlier might allow remote actors to send requests to internal network destinations via a crafted model URL.
Multi Model Server is end of life and no fixed version is available. Users should discontinue use of Multi Model Server and migrate to a supported model serving solution.
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Analysis
by VulDB Data Team • 10/23/2026
The vulnerability identified in Amazon Web Services Multi Model Server versions 1.1.11 and earlier represents a critical server-side request forgery flaw located within the model download functionality. This security defect allows remote, unauthenticated actors to manipulate the application into fetching models from arbitrary URLs controlled by the attacker rather than legitimate sources. By crafting specific requests that exploit this path, an adversary can force the Multi Model Server to initiate HTTP or HTTPS connections to internal network destinations that are typically inaccessible from external networks. This capability effectively turns the vulnerable service into a proxy for accessing restricted resources within the cloud environment, bypassing standard perimeter defenses and network segmentation strategies designed to isolate inference endpoints from sensitive backend infrastructure.
From a technical perspective, this vulnerability is classified under CWE-918 as Server-Side Request Forgery (SSRF). The root cause lies in insufficient validation of user-supplied input used for specifying the model source URL. When the server processes these requests, it fails to enforce strict allow-lists or perform adequate checks against internal IP ranges and private metadata endpoints common in cloud environments such as AWS Instance Metadata Service. Consequently, an attacker can construct a malicious payload that directs the server to communicate with internal services, potentially exposing sensitive configuration data, credentials stored in environment variables, or other microservices running on adjacent instances within the same virtual private cloud. This behavior aligns with ATT&CK technique T1557, specifically Adversary-in-the-Middle, as it facilitates lateral movement and information gathering by leveraging a trusted internal service to interact with other internal components that would otherwise reject direct external connections.
The operational impact of this vulnerability is severe due to the potential for data exfiltration and further network compromise. An attacker who successfully exploits this SSRF flaw can probe the internal network topology, identify running services on non-standard ports, and retrieve sensitive metadata such as temporary security credentials associated with the instance profile. In a production environment hosting machine learning models, this could lead to the theft of proprietary model weights if they are stored in accessible S3 buckets or other cloud storage linked via IAM roles assumed by the server. Furthermore, because Multi Model Server is designed to handle multiple models simultaneously, an attacker might attempt to load maliciously crafted models from external servers that execute arbitrary code upon loading, although the primary risk here remains the network-level SSRF capability which serves as a pivot point for deeper intrusion into the cloud architecture.
Given that Amazon Web Services has declared Multi Model Server end of life and no patched version is available, remediation through patching is not an option. The recommended mitigation strategy requires immediate discontinuation of this software in favor of supported model serving solutions provided by AWS or third-party vendors with active security maintenance cycles. Organizations currently relying on this service should prioritize migration to alternatives such as Amazon SageMaker JumpStart or other containerized inference endpoints that receive regular security updates and adhere to modern secure coding practices. In the interim, if immediate migration is not feasible, network-level controls must be implemented strictly. This includes configuring VPC flow logs to monitor for unusual outbound traffic from these instances, applying strict egress firewall rules to block access to internal IP ranges and metadata endpoints, and ensuring that instance profiles attached to Multi Model Server hosts do not possess overly permissive IAM policies that could exacerbate the impact of a successful exploitation attempt.