CVE-2021-41201

Unitialized access in EinsumHelper::ParseEquation

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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.

for (int i = 0; i < num_inputs; ++i) {
  input_label_counts->at(i).resize(num_labels);
  for (const int label : input_labels->at(i)) {
    if (label != kEllipsisLabel)
      input_label_counts->at(i)[label] += 1;
    else
      input_has_ellipsis->at(i) = true;
  }
}
output_label_counts->resize(num_labels);
for (const int label : *output_labels) {
  if (label != kEllipsisLabel)
    output_label_counts->at(label) += 1;
  else
    *output_has_ellipsis = true;
}

This results in unitialized variable access if callers assume that EinsumHelper::ParseEquation() always sets these flags.

CVE-2021-41201 has a CVSS score of 7.8 (High). The vector is requires local access, low privileges required, and no user interaction. A CVSS score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether this affects your application depends on whether the vulnerable code is present and reachable in your environment. A fixed version is available (2.6.1, 2.5.2, 2.4.4); upgrading removes the vulnerable code path.

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We have patched the issue in GitHub commit f09caa532b6e1ac8d2aa61b7832c78c5b79300c6.

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.

1. What is CVE-2021-41201? CVE-2021-41201 is a high-severity security vulnerability in tensorflow (pip), affecting versions >= 2.6.0, < 2.6.1. It is fixed in 2.6.1, 2.5.2, 2.4.4.
2. How severe is CVE-2021-41201? CVE-2021-41201 has a CVSS score of 7.8 (High). This score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether it represents real risk in your environment depends on whether the vulnerable code is present and reachable.
3. Which packages are affected by CVE-2021-41201?
   • tensorflow (pip) (versions >= 2.6.0, < 2.6.1)
   • tensorflow-cpu (pip) (versions >= 2.6.0, < 2.6.1)
   • tensorflow-gpu (pip) (versions >= 2.6.0, < 2.6.1)
4. Is there a fix for CVE-2021-41201? Yes. CVE-2021-41201 is fixed in 2.6.1, 2.5.2, 2.4.4. Upgrade to this version or later.
5. Is CVE-2021-41201 exploitable, and should I be worried? Whether CVE-2021-41201 is exploitable in your environment depends on whether the vulnerable code is present and reachable. A CVSS score is a worst-case rating; it does not account for your specific deployment, configuration, or usage patterns. Kodem, an Intelligent Application Security platform, uses runtime intelligence to show which vulnerabilities actually execute in production, so you can focus on the ones that represent real risk. Get a demo
6. What actually determines whether CVE-2021-41201 is exploitable, and how bad it is? Exploitability and impact are not fixed properties of a CVE. They depend on runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A high CVSS score on a dependency that never runs is not the same as real risk. Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter.
7. How do I fix CVE-2021-41201?
   • Upgrade tensorflow to 2.6.1 or later
   • Upgrade tensorflow to 2.5.2 or later
   • Upgrade tensorflow to 2.4.4 or later
   • Upgrade tensorflow-cpu to 2.6.1 or later
   • Upgrade tensorflow-cpu to 2.5.2 or later
   • Upgrade tensorflow-cpu to 2.4.4 or later
   • Upgrade tensorflow-gpu to 2.6.1 or later
   • Upgrade tensorflow-gpu to 2.5.2 or later
   • Upgrade tensorflow-gpu to 2.4.4 or later

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