CVE-2021-29543: Google Tensorflow

Medium severity, CVSS 5.5. EPSS: 0.2% chance of exploitation in the next 30 days.

TensorFlow is an end-to-end open source platform for machine learning. An attacker can trigger a denial of service via a `CHECK`-fail in `tf.raw_ops.CTCGreedyDecoder`. This is because the implementation(https://github.com/tensorflow/tensorflow/blob/1615440b17b364b875eb06f43d087381f1460a65/tensorflow/core/kernels/ctc_decoder_ops.cc#L37-L50) has a `CHECK_LT` inserted to validate some invariants. When this condition is false, the program aborts, instead of returning a valid error to the user. This abnormal termination can be weaponized in denial of service attacks. The fix will be included in TensorFlow 2.5.0. We will also cherrypick this commit on TensorFlow 2.4.2, TensorFlow 2.3.3, TensorFlow 2.2.3 and TensorFlow 2.1.4, as these are also affected and still in supported range.

Affected products

• Google Tensorflow: before 2.1.4 (fixed in 2.1.4); from 2.2.0, before 2.2.3 (fixed in 2.2.3); from 2.3.0, before 2.3.3 (fixed in 2.3.3); from 2.4.0, before 2.4.2 (fixed in 2.4.2)

Published 2021-05-14. Last modified 2026-06-17.