CVE-2026-61753

NVIDIA Megatron Bridge, NVIDIA's open-source library for post-training and fine-tuning large language models (part of the NeMo ecosystem), contains a vulnerability in which deserialization of untrusted data can be exploited (CWE-502, with CWE-22 path traversal also cited). The CVSS vector (AV:L/PR:L/UI:N) indicates exploitation requires local access with low privileges and no user interaction, most plausibly triggered when the library deserializes attacker-controlled input such as checkpoints or other serialized training artifacts loaded from an untrusted source. A successful exploit could result in arbitrary code execution, tampering with data, and disclosure of sensitive information on the affected system. Only environments using NVIDIA Megatron Bridge (e.g., ML development, fine-tuning, and training workflows) are affected; no specific affected version ranges were provided in the source data. Exploitation status: no public proof-of-concept, not listed in CISA KEV, and EPSS estimates only a 0.4% probability of exploitation in the next 30 days (30th percentile), indicating low near-term exploitation risk.

What to do: Consult NVIDIA's security bulletin for CVE-2026-61753 to identify the affected and fixed Megatron Bridge versions, and upgrade to the fixed release as soon as practical. Until patched, only load checkpoints and other serialized artifacts from trusted sources and avoid deserializing untrusted or third-party model files in lower-trust environments. Given the local attack vector and low EPSS score, treat this as routine patching rather than an emergency, but monitor NVIDIA and community channels for a public PoC or in-the-wild exploitation.