Does AI Reviewer See the Full Picture? Attacking and Defending Multimodal Peer Review Researchers have introduced PaperGuard, the first comprehensive benchmark designed to systematically evaluate and defend AI-generated peer review against domain-specific, cross-modal attacks. The framework targets vulnerabilities in multimodal large language models used for scientific review, where adversarial manipulation can induce score inflation through both text and figure-based attacks. PaperGuard establishes foundational protocols and a chunk-based embedding defense to address the pervasive vulnerability of AI reviewers in scholarly publishing. arXiv:2606.12716v1 Announce Type: new Abstract: The integration of Large Language Models LLMs and Multimodal LLMs MLLMs into scientific peer-review workflows introduces novel and significant risks for adversarial manipulation, especially given the multimodal nature of scientific papers where figures, not just text, convey core evidence. This creates a significant gap: current robustness studies on AI peer-review are overwhelmingly text-only. Moreover, the problem is distinct from standard jailbreaking, as a peer-review attack seeks to induce a domain-specific, targeted failure e.g., "inflate this score" rather than a general safety policy violation, for which no practical defenses exist. To address this, we introduce PaperGuard, the first comprehensive benchmark designed to systematically evaluate and defend AI-generated peer-review against these domain-specific, cross-modal attacks. Our framework is built on three pillars: 1 a new multimodal peer-review dataset spanning multiple scientific domains; 2 a unified suite of attacks, including black-box prompt injections and white-box perturbations, specifically designed to target both text GCG and figures PGD ; and 3 a practical defense, motivated by the long-context challenge of academic papers, that uses chunk-based embedding search to efficiently localize and mitigate harmful instructions. Our extensive experiments, conducted across state-of-the-art models, confirm that AI reviewers are pervasively vulnerable. PaperGuard establishes the foundational benchmark, protocols, and actionable defense necessary to pioneer trustworthy, attack-resilient AI-assisted scholarly reviewing.