CVE-2021-37691: TensorFlow TFLite division by zero in LSH operation

CVE-2021-37691 · Severity: low · CVSS 3.1 · Published 2021-08-12

TensorFlow is a machine learning library that includes TFLite, a lightweight runtime for deploying neural networks. An attacker can craft a specially designed model that triggers a division-by-zero crash in the LSH (Locality Sensitive Hashing) implementation, causing the application to crash and become unavailable. This affects anyone running TensorFlow-based applications that load untrusted models.

Technologies: Google TensorFlow, tensorflow (PyPI), tensorflow-cpu (PyPI), tensorflow-gpu (PyPI). Vendors: Google, PyPI.

Quick answers

Is CVE-2021-37691 exploited in the wild?
No. Junglewise Threat Intelligence has no report of CVE-2021-37691 being exploited in the wild.
How severe is CVE-2021-37691?
Low severity, with a CVSS score of 3.1, published 12 August 2021.
Which products and versions are affected?
Google TensorFlow < 2.3.4, 2.4.0-2.4.2, 2.5.0; tensorflow (PyPI) GIT:introduced=0,fixed=0575b640091680cfb70f4dd93e70658de43b94f9|ECOSYSTEM:introduced=2.3.0,fixed=2.3.4,introduced=2.4.0,fixed=2.4.3; tensorflow-cpu (PyPI) GIT:introduced=0,fixed=0575b640091680cfb70f4dd93e70658de43b94f9|ECOSYSTEM:introduced=2.3.0,fixed=2.3.4,introduced=2.4.0,fixed=2.4.3; tensorflow-gpu (PyPI) GIT:introduced=0,fixed=0575b640091680cfb70f4dd93e70658de43b94f9|ECOSYSTEM:introduced=2.3.0,fixed=2.3.4,introduced=2.4.0,fixed=2.4.3.
Is there a fix for CVE-2021-37691?
Yes. tensorflow (PyPI): upgrade to 2.4.3 or later; tensorflow-cpu (PyPI): upgrade to 2.4.3 or later; tensorflow-gpu (PyPI): upgrade to 2.4.3 or later. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.
How is CVE-2021-37691 attacked?
It is attacked with local access.
Am I affected by CVE-2021-37691?
Check whether you run Google TensorFlow, tensorflow (PyPI), tensorflow-cpu (PyPI) or one of the others listed at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

How to fix

  • tensorflow (PyPI): upgrade to 2.4.3 or later
    pip install "tensorflow>=2.4.3"
  • tensorflow-cpu (PyPI): upgrade to 2.4.3 or later
    pip install "tensorflow-cpu>=2.4.3"
  • tensorflow-gpu (PyPI): upgrade to 2.4.3 or later
    pip install "tensorflow-gpu>=2.4.3"

Technical details

The vulnerability is a division-by-zero error (CWE-369) in the LSH operation within TFLite. The vulnerable code divides by the first dimension of the input tensor without checking that it is non-zero: `int input_item_bytes = input->bytes / SizeOfDimension(input, 0)`. An attacker can craft a malicious TFLite model with a zero-sized first dimension to trigger this crash. The attack requires only the ability to provide a model file to the application; no special privileges or user interaction are needed once the model is loaded. This results in a denial-of-service condition. Patches are available in TensorFlow 2.3.4, 2.4.3, 2.5.1, and 2.6.0.

Affected products

  • Google TensorFlow < 2.3.4, 2.4.0-2.4.2, 2.5.0
  • Google TensorFlow CPU < 2.3.4, 2.4.0-2.4.2, 2.5.0
  • Google TensorFlow GPU < 2.3.4, 2.4.0-2.4.2, 2.5.0

Identifiers

  • CVE-2021-37691
  • GHSA-27qf-jwm8-g7f3
  • PYSEC-2021-313
  • PYSEC-2021-604
  • PYSEC-2021-802

Timeline

  • 2021-08-11: disclosed: Advisory published
  • 2021-08: patched: Patches released in TensorFlow 2.3.4, 2.4.3, 2.5.1, and 2.6.0

References

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