Google Vertex AI SDK Flaw Let Attackers Hijack Model Uploads via Bucket Squatting
Jun 16, 2026
Machine Learning / Cloud Security
A flaw in the Google Cloud Vertex AI SDK for Python let an attacker with no access to a victim's project hijack the victim's machine learning model upload and run code inside Google's serving infrastructure. Palo Alto Networks Unit 42, which found and reported the bug through Google's bug bounty program, calls the technique " Pickle in the Middle " and said it saw no exploitation in the wild. Google has patched it; if you use the SDK, update to version 1.148.0 or later. The attacker needed only a Google Cloud project of their own and the victim's project ID, which is often public. No credentials, no phishing, no foothold in the target. The flaw was in how the SDK chose a temporary Cloud Storage bucket for model uploads. If a user did not set a bucket, the SDK generated a predictable name from the project ID and region, such as project-vertex-staging-region . It checked whether that bucket existed, but not whether the victim owned it. Because buc...
