OMNIGUARD: An Efficient Approach for AI Safety Moderation Across
  Modalities
Authors: name: Sahil Verma; name: Keegan Hines; name: Jeff Bilmes; name: Charlotte Siska; name: Luke Zettlemoyer; name: Hila Gonen; name: Chandan Singh
Published: 2025-05-29 05:25:27

Abstract: The emerging capabilities of large language models (LLMs) have sparked
concerns about their immediate potential for harmful misuse. The core approach
to mitigate these concerns is the detection of harmful queries to the model.
Current detection approaches are fallible, and are particularly susceptible to
attacks that exploit mismatched generalization of model capabilities (e.g.,
prompts in low-resource languages or prompts provided in non-text modalities
such as image and audio). To tackle this challenge, we propose OMNIGUARD, an
approach for detecting harmful prompts across languages and modalities. Our
approach (i) identifies internal representations of an LLM/MLLM that are
aligned across languages or modalities and then (ii) uses them to build a
language-agnostic or modality-agnostic classifier for detecting harmful
prompts. OMNIGUARD improves harmful prompt classification accuracy by 11.57\%
over the strongest baseline in a multilingual setting, by 20.44\% for
image-based prompts, and sets a new SOTA for audio-based prompts. By
repurposing embeddings computed during generation, OMNIGUARD is also very
efficient (approx 120 times faster than the next fastest baseline). Code
and data are available at: https://github.com/vsahil/OmniGuard.