---
id: CVE-2020-26270
aliases:
  - GHSA-m648-33qf-v3gp
  - BIT-tensorflow-2020-26270
  - PYSEC-2020-256
  - PYSEC-2020-301
  - PYSEC-2020-336
title: CHECK-fail in LSTM with zero-length input in TensorFlow
summary: CHECK-fail in LSTM with zero-length input in TensorFlow
severity: medium
cvss: 4.4
cvssVector: 'CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:L/A:L'
vendor: tensorflow
product: tensorflow
ecosystem: pip
affected:
  - tensorflow < 1.15.5
  - 'tensorflow >= 2.0.0, < 2.0.4'
  - 'tensorflow >= 2.1.0, < 2.1.3'
  - 'tensorflow >= 2.2.0, < 2.2.2'
  - 'tensorflow >= 2.3.0, < 2.3.2'
  - tensorflow-cpu < 1.15.5
  - 'tensorflow-cpu >= 2.0.0, < 2.0.4'
  - 'tensorflow-cpu >= 2.1.0, < 2.1.3'
  - 'tensorflow-cpu >= 2.2.0, < 2.2.2'
  - 'tensorflow-cpu >= 2.3.0, < 2.3.2'
  - tensorflow-gpu < 1.15.5
  - 'tensorflow-gpu >= 2.0.0, < 2.0.4'
  - 'tensorflow-gpu >= 2.1.0, < 2.1.3'
  - 'tensorflow-gpu >= 2.2.0, < 2.2.2'
  - 'tensorflow-gpu >= 2.3.0, < 2.3.2'
patched:
  - tensorflow 1.15.5
  - tensorflow 2.0.4
  - tensorflow 2.1.3
  - tensorflow 2.2.2
  - tensorflow 2.3.2
  - tensorflow-cpu 1.15.5
  - tensorflow-cpu 2.0.4
  - tensorflow-cpu 2.1.3
  - tensorflow-cpu 2.2.2
  - tensorflow-cpu 2.3.2
  - tensorflow-gpu 1.15.5
  - tensorflow-gpu 2.0.4
  - tensorflow-gpu 2.1.3
  - tensorflow-gpu 2.2.2
  - tensorflow-gpu 2.3.2
published: '2020-12-10'
updated: '2026-07-08'
source: OSV
sourceUrl: 'https://osv.dev/vulnerability/GHSA-m648-33qf-v3gp'
references:
  - url: >-
      https://github.com/tensorflow/tensorflow/security/advisories/GHSA-m648-33qf-v3gp
  - url: 'https://nvd.nist.gov/vuln/detail/CVE-2020-26270'
  - url: >-
      https://github.com/tensorflow/tensorflow/commit/14755416e364f17fb1870882fa778c7fec7f16e3
  - url: >-
      https://github.com/pypa/advisory-database/tree/main/vulns/tensorflow-cpu/PYSEC-2020-301.yaml
  - url: >-
      https://github.com/pypa/advisory-database/tree/main/vulns/tensorflow-gpu/PYSEC-2020-336.yaml
  - url: >-
      https://github.com/pypa/advisory-database/tree/main/vulns/tensorflow/PYSEC-2020-256.yaml
  - url: 'https://github.com/tensorflow/tensorflow'
tags:
  - osv
  - pip
epss: 0.00173
epssPercentile: 0.05967
ingestedAt: '2026-07-08T18:25:51.140Z'
---

## Overview

### Impact
Running an LSTM/GRU model where the LSTM/GRU layer receives an input with zero-length results in a `CHECK` failure when using the CUDA backend.

This can result in a query-of-death vulnerability, via denial of service, if users can control the input to the layer.

### Patches
We have patched the issue in GitHub commit [14755416e364f17fb1870882fa778c7fec7f16e3](https://github.com/tensorflow/tensorflow/commit/14755416e364f17fb1870882fa778c7fec7f16e3) and will release TensorFlow 2.4.0 containing the patch. TensorFlow nightly packages after this commit will also have the issue resolved.

Since this issue also impacts TF versions before 2.4, we will patch all releases between 1.15 and 2.3 inclusive.

### For more information
Please consult [our security guide](https://github.com/tensorflow/tensorflow/blob/master/SECURITY.md) for more information regarding the security model and how to contact us with issues and questions.

## Affected packages

- `tensorflow < 1.15.5`
- `tensorflow >= 2.0.0, < 2.0.4`
- `tensorflow >= 2.1.0, < 2.1.3`
- `tensorflow >= 2.2.0, < 2.2.2`
- `tensorflow >= 2.3.0, < 2.3.2`
- `tensorflow-cpu < 1.15.5`
- `tensorflow-cpu >= 2.0.0, < 2.0.4`
- `tensorflow-cpu >= 2.1.0, < 2.1.3`
- `tensorflow-cpu >= 2.2.0, < 2.2.2`
- `tensorflow-cpu >= 2.3.0, < 2.3.2`
- `tensorflow-gpu < 1.15.5`
- `tensorflow-gpu >= 2.0.0, < 2.0.4`
- `tensorflow-gpu >= 2.1.0, < 2.1.3`
- `tensorflow-gpu >= 2.2.0, < 2.2.2`
- `tensorflow-gpu >= 2.3.0, < 2.3.2`

## Remediation

Upgrade to a patched release:

- `tensorflow 1.15.5`
- `tensorflow 2.0.4`
- `tensorflow 2.1.3`
- `tensorflow 2.2.2`
- `tensorflow 2.3.2`
- `tensorflow-cpu 1.15.5`
- `tensorflow-cpu 2.0.4`
- `tensorflow-cpu 2.1.3`
- `tensorflow-cpu 2.2.2`
- `tensorflow-cpu 2.3.2`
- `tensorflow-gpu 1.15.5`
- `tensorflow-gpu 2.0.4`
- `tensorflow-gpu 2.1.3`
- `tensorflow-gpu 2.2.2`
- `tensorflow-gpu 2.3.2`