CVE-2020-26270: CHECK-fail in LSTM with zero-length input in TensorFlow
Summary
CVE-2020-26270: CHECK-fail in LSTM with zero-length input in TensorFlow. Affects tensorflow across 5 version ranges.
< 1.15.5
>= 2.0.0, < 2.0.4
>= 2.1.0, < 2.1.3
>= 2.2.0, < 2.2.2
>= 2.3.0, < 2.3.2
Fixed in 5 releases; the minimum fixed version depends on the release line you run. How to fix ↓
Also tracked for
- tensorflow · Bitnami
- tensorflow-cpu · PyPI
- tensorflow-gpu · PyPI
The same CVE-2020-26270 is tracked separately for each ecosystem and vendor. Its fix information is the same; the package and affected versions differ.
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Background
TensorFlow is an open-source machine learning framework widely used for various applications, including deep learning models. It provides a comprehensive ecosystem for building and deploying machine learning models. However, a vulnerability has been identified in TensorFlow versions 1.15 to 2.3, which can lead to a denial of service attack if an attacker can control the input to the LSTM/GRU layer. This vulnerability occurs when running an LSTM/GRU model with a zero-length input using the CUDA backend.
Vulnerability Detail
The vulnerability arises due to a CHECK failure in the LSTM/GRU layer when it receives an input with zero length. This issue impacts TensorFlow versions 1.15 to 2.3. If an attacker can manipulate the input to the layer, they can trigger a denial of service attack, potentially leading to a query-of-death vulnerability. The vulnerability has a CVSS score of 4.4, indicating a low severity level.
How To Fix
Latest published version: 2.21.0 as of 22 Oct 2026
pip install --upgrade "tensorflow==2.21.0"Upgrading to it may include breaking changes; the versions below are the minimum fixed release for this vulnerability.
If you can't move to the latest
The minimum fixed version depends on the release line you run.
-
< 1.15.51.15.5pip install --upgrade "tensorflow==1.15.5" -
>= 2.0.0, < 2.0.42.0.4pip install --upgrade "tensorflow==2.0.4" -
>= 2.1.0, < 2.1.32.1.3pip install --upgrade "tensorflow==2.1.3" -
>= 2.2.0, < 2.2.22.2.2pip install --upgrade "tensorflow==2.2.2" -
>= 2.3.0, < 2.3.22.3.2pip install --upgrade "tensorflow==2.3.2"
Tip — Not sure which release line you're on? Vulert can find the fix for the version you are using. Scan free →
Workaround
There is no specific workaround mentioned for this vulnerability.
Conclusion
The identified vulnerability in TensorFlow versions 1.15 to 2.3 can lead to a denial of service attack if an attacker can manipulate the input to the LSTM/GRU layer. To mitigate this vulnerability, it is recommended to update to TensorFlow 2.4.0 or later. Patches will also be provided for versions between 1.15 and 2.3. For further assistance and support on vulnerability remediation, please contact DevNack.com.
See every vulnerability recorded for tensorflow →
FAQ
The vulnerability can result in a denial of service attack if an attacker can control the input to the LSTM/GRU layer. This can lead to a query-of-death vulnerability, causing a potential disruption of service.
The vulnerability impacts TensorFlow versions 1.15 to 2.3, inclusive.
To fix this vulnerability, update your TensorFlow installation to version 2.4.0 or later. Patches will also be provided for versions between 1.15 and 2.3.
No specific workaround has been mentioned for this vulnerability.
The vulnerability has a CVSS score of 4.4, indicating a low severity level.
References
Related vulnerabilities
Recent vulnerabilities recorded for tensorflow.
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