CVE-2021-37681

Description

TensorFlow is an end-to-end open source platform for machine learning. In affected versions the implementation of SVDF in TFLite is [vulnerable to a null pointer error](https://github.com/tensorflow/tensorflow/blob/460e000de3a83278fb00b61a16d161b1964f15f4/tensorflow/lite/kernels/svdf.cc#L300-L313). The [`GetVariableInput` function](https://github.com/tensorflow/tensorflow/blob/460e000de3a83278fb00b61a16d161b1964f15f4/tensorflow/lite/kernels/kernel_util.cc#L115-L119) can return a null pointer but `GetTensorData` assumes that the argument is always a valid tensor. Furthermore, because `GetVariableInput` calls [`GetMutableInput`](https://github.com/tensorflow/tensorflow/blob/460e000de3a83278fb00b61a16d161b1964f15f4/tensorflow/lite/kernels/kernel_util.cc#L82-L90) which might return `nullptr`, the `tensor->is_variable` expression can also trigger a null pointer exception. We have patched the issue in GitHub commit 5b048e87e4e55990dae6b547add4dae59f4e1c76. The fix will be included in TensorFlow 2.6.0. We will also cherrypick this commit on TensorFlow 2.5.1, TensorFlow 2.4.3, and TensorFlow 2.3.4, as these are also affected and still in supported range.

How to fix CVE-2021-37681

To remediate CVE-2021-37681, upgrade the affected package to a fixed version below.

• —upgrade to 2.3.4 or later
• —upgrade to 2.3.4 or later
• —upgrade to 5b048e87e4e55990dae6b547add4dae59f4e1c76 or later
• —upgrade to 5b048e87e4e55990dae6b547add4dae59f4e1c76 or later
• —upgrade to 2.3.4 or later
• —upgrade to 5b048e87e4e55990dae6b547add4dae59f4e1c76 or later
• —upgrade to 2.3.4 or later

Is CVE-2021-37681 being exploited?

Low — EPSS is 0.0%, meaning exploitation activity has not been observed at scale.

Affected packages (7)

• >= 2.3.0, < 2.3.4, >= 2.4.0, < 2.4.3, >= 2.5.0, < 2.5.1
• from 0, < 2.3.4
• from 0, < 5b048e87e4e55990dae6b547add4dae59f4e1c76 | >= 2.3.0, < 2.3.4, >= 2.4.0, < 2.4.3
• from 0, < 5b048e87e4e55990dae6b547add4dae59f4e1c76 | >= 2.3.0, < 2.3.4, >= 2.4.0, < 2.4.3
• from 0, < 2.3.4
• from 0, < 5b048e87e4e55990dae6b547add4dae59f4e1c76 | >= 2.3.0, < 2.3.4, >= 2.4.0, < 2.4.3
• from 0, < 2.3.4

CVSS scores

References (8)

• ADVISORYnvd.nist.gov/vuln/detail/CVE-2021-37681
• PATCHgithub.com/tensorflow/tensorflow
• WEBgithub.com/pypa/advisory-database/tree/main/vulns/tensorflow-cpu/PYSEC-2021-594.yaml
• WEBgithub.com/pypa/advisory-database/tree/main/vulns/tensorflow-gpu/PYSEC-2021-792.yaml