CVE-2021-37678: Arbitrary code execution due to YAML deserialization
Impact TensorFlow and Keras can be tricked to perform arbitrary code execution when deserializing a Keras model from YAML format.
python from tensorflow.keras import models
payload = ''' !!python/object/new:type args: ['z', !!python/tuple [], {'extend': !!python/name:exec }] listitems: "import('os').system('cat /etc/passwd')" ''' models.modelfromyaml(payload) The implementation uses yaml.unsafeload which can perform arbitrary code execution on the input.
Patches Given that YAML format support requires a significant amount of work, we have removed it for now.
We have patched the issue in GitHub commit 23d6383eb6c14084a8fc3bdf164043b974818012.
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.
For more information Please consult our security guide for more information regarding the security model and how to contact us with issues and questions.
Attribution This vulnerability has been reported by Arjun Shibu.
Other sources
TensorFlow is an end-to-end open source platform for machine learning. In affected versions TensorFlow and Keras can be tricked to perform arbitrary code execution when deserializing a Keras model from YAML format. The implementation uses yaml.unsafeload which can perform arbitrary code execution on the input. Given that YAML format support requires a significant amount of work, we have removed it for now. We have patched the issue in GitHub commit 23d6383eb6c14084a8fc3bdf164043b974818012. 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.
Affected Software
Remediation
Recommended actions to resolve this vulnerability, in priority order.
- Upgrade
Upgrade
pip/tensorflow-gputo a version that resolves this vulnerability.Fixed in 2.5.1 - Upgrade
Upgrade
pip/tensorflow-gputo a version that resolves this vulnerability.Fixed in 2.4.3 - Upgrade
Upgrade
pip/tensorflow-gputo a version that resolves this vulnerability.Fixed in 2.3.4 - Upgrade
Upgrade
pip/tensorflow-cputo a version that resolves this vulnerability.Fixed in 2.5.1 - Upgrade
Upgrade
pip/tensorflow-cputo a version that resolves this vulnerability.Fixed in 2.4.3 - Upgrade
Upgrade
pip/tensorflow-cputo a version that resolves this vulnerability.Fixed in 2.3.4 - Upgrade
Upgrade
pip/tensorflowto a version that resolves this vulnerability.Fixed in 2.5.1 - Upgrade
Upgrade
pip/tensorflowto a version that resolves this vulnerability.Fixed in 2.4.3 - Upgrade
Upgrade
pip/tensorflowto a version that resolves this vulnerability.Fixed in 2.3.4 - Upgrade
Upgrade
TensorFlowto a version that resolves this vulnerability.Fixed in 2.6.0Patch 23d6383eb6c14084a8fc3bdf164043b974818012 - Upgrade
Upgrade
TensorFlowto a version that resolves this vulnerability.Fixed in 2.5.1Patch 23d6383eb6c14084a8fc3bdf164043b974818012 - Upgrade
Upgrade
TensorFlowto a version that resolves this vulnerability.Fixed in 2.4.3 - Upgrade
Upgrade
TensorFlowto a version that resolves this vulnerability.Fixed in 2.3.4 - Configuration
Do not use YAML deserialization paths that rely on `yaml.unsafe_load` for Keras model loading; ensure YAML model deserialization is performed using the patched/safe implementation.
TensorFlow/Keras model YAML loading yaml.unsafe_load = disable or avoid use of yaml.unsafe_load when deserializing Keras models from YAML - Compensating control
Given that YAML format support requires a significant amount of work, the text indicates YAML format support has been removed for now—remove/disable YAML support for Keras model deserialization in your environment until patched.
Event History
Frequently Asked Questions
What is the severity of CVE-2021-37678?
CVE-2021-37678 is classified as a high-severity vulnerability due to its potential for arbitrary code execution.
How do I fix CVE-2021-37678?
To remediate CVE-2021-37678, upgrade TensorFlow to versions 2.5.1 or later.
Which versions of TensorFlow are affected by CVE-2021-37678?
CVE-2021-37678 affects TensorFlow versions prior to 2.5.1, including 2.5.0, 2.4.x, and 2.3.x.
What type of vulnerability is CVE-2021-37678?
CVE-2021-37678 is a deserialization vulnerability that could allow arbitrary code execution.
Can Keras models trigger CVE-2021-37678?
Yes, CVE-2021-37678 can be triggered when deserializing Keras models from YAML format.