Keras vulnerable to DoS via Malicious .keras Model (HDF5 Shape Bomb Causes Petabyte Allocation in KerasFileEditor)
Date: 2026-05
Affected: pip/keras, pip/keras
Attack vector: dos
Category: vulnerability-disclosure
Severity: High
CVE: CVE-2026-0897
CWE: CWE-770

### Summary Keras’s model loader (KerasFileEditor) unsafely loads user-supplied .keras model files containing HDF5-based weight files without performing any validation on HDF5 dataset metadata. An attacker can craft a .keras archive containing a valid model.weights.h5 file whose dataset declares an extremely large shape (e.g. (50_000_000, 50_000_000)), but stores only a few bytes. The .keras file remains small (100–400 KB) because HDF5 with gzip compression stores minimal data. During model loading, Keras executes: `python result[key] = value[()] # loads entire dataset into memory` value[()] instructs h5py to allocate RAM proportional to the dataset’s declared shape – in this case 8.88 PiB of memory. This results in: Immediate memory exhaustion Python / TensorFlow crashes Jupyter kernel kill System instability Full Denial of Service on any workload that processes untrusted .keras models This allows an attacker to crash any environment or pipeline that loads .keras models, including MLOps backends, training services, model upload endpoints, or automated pipelines. ### Proof of Concept ``` // PoC.py import zipfile import io import h5py import numpy as np from keras.saving import KerasFileEditor # Create a malicious .keras model containing a massive HDF5 shape bomb def create_malicious_keras(path="bomb.keras"): hdf5_bytes = io.BytesIO() # Create an HDF5 file with a huge declared dataset shape with h5py.File(hdf5_bytes, "w") as f: d = f.create_dataset(


Mitigations:

Architectural layers (MAESTRO):