CVE-2021-41201: Unitialized access in `EinsumHelper::ParseEquation`

Severity: high (CVSS 7.8 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.2% probability of exploitation in the next 30 days
Public exploit or detection template: yes
Published: 2021-11-05 · updated 2026-06-17
Weakness: CWE-824

Description

TensorFlow is an open source platform for machine learning. In affeced versions during execution, `EinsumHelper::ParseEquation()` is supposed to set the flags in `input_has_ellipsis` vector and `*output_has_ellipsis` boolean to indicate whether there is ellipsis in the corresponding inputs and output. However, the code only changes these flags to `true` and never assigns `false`. This results in unitialized variable access if callers assume that `EinsumHelper::ParseEquation()` always sets these flags. The fix will be included in TensorFlow 2.7.0. We will also cherrypick this commit on TensorFlow 2.6.1, TensorFlow 2.5.2, and TensorFlow 2.4.4, as these are also affected and still in supported range.

Affected products

tensorflow: before 2.4.4; from 2.5.0 before 2.5.2; 2.6.0 — fixed in 2.4.4, 2.5.2

How to fix

Upgrade to a fixed version: tensorflow 2.4.4, 2.5.2. Check the vendor advisory for mitigations.

References

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