CVE-2021-37670: Heap OOB in `UpperBound` and `LowerBound` in TensorFlow

Severity: medium (CVSS 5.5 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: none known
Published: 2021-08-12 · updated 2026-06-17
Weakness: CWE-125

Description

TensorFlow is an end-to-end open source platform for machine learning. In affected versions an attacker can read from outside of bounds of heap allocated data by sending specially crafted illegal arguments to `tf.raw_ops.UpperBound`. The [implementation](https://github.com/tensorflow/tensorflow/blob/460e000de3a83278fb00b61a16d161b1964f15f4/tensorflow/core/kernels/searchsorted_op.cc#L85-L104) does not validate the rank of `sorted_input` argument. A similar issue occurs in `tf.raw_ops.LowerBound`. We have patched the issue in GitHub commit 42459e4273c2e47a3232cc16c4f4fff3b3a35c38. 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 products

tensorflow: from 2.3.0 before 2.3.4; from 2.4.0 before 2.4.3; 2.5.0, 2.6.0-rc0, 2.6.0-rc1, 2.6.0-rc2 — fixed in 2.3.4, 2.4.3

How to fix

Upgrade to a fixed version: tensorflow 2.3.4, 2.4.3. Check the vendor advisory for mitigations.

References

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