- Palo Alto found critical flaws in AI/ML libraries NeMo, Uni2TS and FlexTok
- Vulnerabilities allowed arbitrary code execution via malicious model metadata
- All patched by mid-2025; no exploitation was observed after December 2025
Security researchers at Palo Alto Networks have discovered vulnerabilities used in some leading artificial intelligence (AI) and machine learning (ML) tools that, if abused, could allow threat actors to execute malicious code on target endpoints, remotely.
In a security advisory, researchers said that around April 2025 they discovered bugs in three open source Python libraries published by Apple, Salesforce and NVIDIA in their GitHub repositories.
The libraries are called NeMo, Uni2TS and FlexTok. NeMo is a PyTorch-based research framework, Uni2TS a PyTorch library for research used by Salesforce’s Morai, and FlexTok is a Python-based research framework, which allows AL and ML models to process images. In total, they have over 10 million downloads on HuggingFace (a platform that hosts open source AI models and other tools).
Fixed bugs
“The vulnerabilities come from libraries that use metadata to configure complex models and pipelines, where a third-party shared library instantiates classes using this metadata,” Palo Alto explained in its advisory.
“Vulnerable versions of these libraries simply execute the provided data as code. This allows an attacker to embed arbitrary code in the model metadata, which would be automatically executed when the vulnerable libraries load these modified models.”
All three developers were notified in April 2025, and by the end of July they were all fixed. NVIDIA issued CVE-2025-23304 and gave it a high severity rating (7.8/10) and released a fix in NeMo 2.3.2. FlexTok updated its code in June 2025, while Salesforce issued CVE-2026-22584, gave it a critical rating (9.8/10), and fixed it in July 2025.
Palo Alto says that as of December 2025, there is no evidence that these vulnerabilities are being abused in the wild. All errors were discovered by the company’s Prisma AIRS tool.
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