CVE-2026-61774

NVIDIA Megatron Bridge, NVIDIA's library for large-scale language-model training within the NeMo ecosystem, contains a deserialization vulnerability (CWE-502) in which untrusted serialized data is deserialized without sufficient validation. The CVSS 3.1 vector (AV:L/PR:L/UI:N) indicates exploitation requires local access or low-level privileges and no user interaction, consistent with an attacker supplying or tampering with serialized input such as an artifact the library loads. A successful exploit could allow code execution on the host, tampering with data, and disclosure of sensitive information such as model weights or training artifacts. Anyone running NVIDIA Megatron Bridge for model training or fine-tuning is potentially affected; the available data does not specify affected version ranges. Exploitation status: no public proof-of-concept, not listed in CISA KEV, and EPSS estimates only a 0.2% probability of exploitation within 30 days.

What to do: Review NVIDIA's security advisory for CVE-2026-61774 and upgrade Megatron Bridge to the fixed release it specifies (no version numbers were provided in the available data). Until patched, only deserialize checkpoints and other artifacts from trusted sources, and restrict local access to hosts running the library. Given the low EPSS score and absence of known exploits, standard patch-cycle prioritization is reasonable unless the library runs in shared or internet-reachable training environments.