Oasis Security has disclosed a serious flaw in NVIDIA NemoClaw that lets an attacker take over a local Ollama instance simply by getting the victim to open a webpage. The attack silently implants hidden instructions into the AI model’s chat templates, affecting every future conversation without any visible signs to the user or client application.
The target is NVIDIA NemoClaw, an open-source AI agent reference stack that many teams run locally with Ollama as the inference backend. On Windows, NemoClaw starts Ollama with OLLAMA_HOST=0.0.0.0:11434, exposing the unauthenticated API to all network interfaces. Because the binding is not restricted to 127.0.0.1, Host header validation is bypassed and CORS allows requests from attacker-controlled domains.
The final step uses classic DNS rebinding: the attacker’s domain first resolves to their server and then to 127.0.0.1. The browser believes it is still talking to the same origin, allowing JavaScript on the page to reach the local Ollama API. This technique had already been addressed by Ollama in 2024 under CVE-2024-28224, but NemoClaw’s configuration reopens the exposure.
Once API access is obtained, the attacker does not exfiltrate data. Instead, they abuse the /api/create endpoint to upload a modified Go template that controls how message arrays are rendered. The tampered template appends attacker-chosen instructions after every system message during inference. The poisoned behavior persists across all sessions and even when the agent changes its own system prompt.
Oasis Security emphasized that clients cannot detect or block the change because the template is an internal model-layer property invisible to API callers. The compromise also hands attackers all permissions granted to the agent, including code execution, file access, and internal network reach.
No CVE identifier has been issued and no official fix is available. As of 25 August, no in-the-wild exploitation has been observed. The 10 August v0.0.106 release added a bind probe that refuses to start if Ollama is not bound to loopback, yet the check does not cover the 0.0.0.0 case on Windows and can be disabled with the environment variable NEMOCLAW_OLLAMA_PROXY_SKIP_BIND_PROBE=1.
Security teams running local AI agent stacks are advised to verify that Ollama listens only on 127.0.0.1, avoid exposing port 11434, monitor NVIDIA NemoClaw updates, and implement integrity checks on model files and templates at startup.
