CVE-2026-24186: NVIDIA FLARE SDK RCE Vulnerability

CVE-2026-24186 Overview

CVE-2026-24186 is a high-severity insecure deserialization vulnerability affecting the NVIDIA FLARE SDK. The vulnerability exists within the FOBS (Federated Object Binary Serialization) component, where an attacker may cause deserialization of untrusted data by sending a malicious FOBS-encoded message. A successful exploit of this vulnerability could lead to arbitrary code execution on the target system.

NVIDIA FLARE (Federated Learning Application Runtime Environment) is an open-source SDK designed for federated learning workflows. The FOBS component handles serialization and deserialization of objects for communication between federated learning participants. This vulnerability allows remote attackers with low-privilege access to potentially execute malicious code by crafting specially designed serialized payloads.

Critical Impact
Remote attackers can achieve code execution by sending malicious FOBS-encoded messages, potentially compromising federated learning infrastructure and sensitive model data.

Affected Products

NVIDIA FLARE SDK (specific versions affected - consult NVIDIA Support Response for details)

Discovery Timeline

2026-04-28 - CVE-2026-24186 published to NVD
2026-04-28 - Last updated in NVD database

Technical Details for CVE-2026-24186

Vulnerability Analysis

This vulnerability is classified as CWE-502: Deserialization of Untrusted Data. The FOBS component in NVIDIA FLARE SDK processes serialized objects without adequate validation, creating an opportunity for attackers to inject malicious payloads that execute arbitrary code during the deserialization process.

In federated learning architectures, participants communicate by exchanging serialized objects containing model updates, gradients, and other computational data. When the FOBS deserializer processes incoming messages without proper integrity checks, an attacker can craft a malicious serialized object that, when deserialized, instantiates dangerous classes or triggers code execution paths.

The network-based attack vector combined with low privilege requirements makes this vulnerability particularly dangerous in distributed federated learning deployments where multiple parties exchange data over potentially untrusted networks.

Root Cause

The root cause of CVE-2026-24186 lies in the FOBS component's failure to properly validate and sanitize serialized data before deserialization. The deserializer accepts arbitrary class instantiation without maintaining an allowlist of safe classes or performing integrity verification on incoming payloads. This classic insecure deserialization pattern allows attackers to leverage existing classes in the application's classpath (sometimes called "gadget chains") to achieve code execution.

Attack Vector

The attack leverages the network-accessible nature of NVIDIA FLARE's federated learning communication channels. An attacker with low-level access to the federated learning network can intercept or inject FOBS-encoded messages containing malicious serialized objects.

The exploitation flow typically involves:

The attacker identifies a FLARE SDK deployment accepting FOBS-encoded messages
A malicious serialized payload is crafted using available gadget classes within the SDK's dependencies
The payload is sent as a FOBS-encoded message to a target participant or server
Upon deserialization, the malicious object triggers code execution in the context of the FLARE application

Due to the sensitive nature of this vulnerability, specific exploitation code is not provided. Technical details regarding the vulnerability mechanism can be found in the NVIDIA Support Response.

Detection Methods for CVE-2026-24186

Indicators of Compromise

Unusual or malformed FOBS-encoded messages in network traffic logs
Unexpected process spawning or child processes from FLARE SDK applications
Anomalous network connections originating from federated learning infrastructure
Evidence of serialization/deserialization errors in application logs followed by suspicious activity

Detection Strategies

Implement deep packet inspection for FOBS-encoded traffic to identify anomalous serialized payloads
Deploy endpoint detection and response (EDR) solutions like SentinelOne to monitor for post-exploitation behaviors such as unexpected code execution
Establish baseline behavior for FLARE SDK processes and alert on deviations
Monitor for known deserialization gadget class instantiation patterns in application memory

Monitoring Recommendations

Enable verbose logging for FOBS message processing to capture serialization events
Implement network segmentation monitoring between federated learning participants
Deploy file integrity monitoring on FLARE SDK installation directories
Configure alerts for unexpected outbound connections from FLARE infrastructure components

How to Mitigate CVE-2026-24186

Immediate Actions Required

Review the NVIDIA Support Response for official patch availability and upgrade instructions
Restrict network access to FLARE SDK deployments using firewall rules and network segmentation
Implement mutual TLS authentication between all federated learning participants
Audit all participants in your federated learning network for potential compromise

Patch Information

NVIDIA has released security guidance addressing this vulnerability. Organizations running affected versions of NVIDIA FLARE SDK should consult the NVIDIA Support Response for specific patch details, affected version information, and upgrade procedures. Additionally, the NVD CVE-2026-24186 Detail page provides supplementary vulnerability information.

Workarounds

Implement network-level controls to restrict which hosts can send FOBS-encoded messages to FLARE deployments
Deploy a reverse proxy or application firewall capable of inspecting and filtering serialized payloads
If feasible, implement custom serialization filters to allowlist only expected classes for deserialization
Consider temporarily disabling or isolating vulnerable FLARE SDK instances until patches can be applied

bash

# Example: Network restriction for FLARE SDK (adjust IPs and ports as needed)
# Restrict FOBS communication to trusted federated learning participants only
iptables -A INPUT -p tcp --dport 8002 -s 10.0.0.0/24 -j ACCEPT
iptables -A INPUT -p tcp --dport 8002 -j DROP