Crash in `tf.strings.substr` due to `CHECK`-fail

Low2.5CVE-2021-29617 · Published May 21, 2021 · updated Jul 8, 2026

### Impact An attacker can cause a denial of service via `CHECK`-fail in `tf.strings.substr` with invalid arguments: ```python import tensorflow as tf tf.strings.substr(input='abc', len=1, pos=[1,-1]) ``` ```python import tensorflow as tf tf.strings.substr(input='abc', len=1, pos=[1,2]) ``` ### Patches We have received a patch for the issue in GitHub commit [890f7164b70354c57d40eda52dcdd7658677c09f](https://github.com/tensorflow/tensorflow/commit/890f7164b70354c57d40eda52dcdd7658677c09f). 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. ### For more information Please consult [our security guide](https://github.com/tensorflow/tensorflow/blob/master/SECURITY.md) for more information regarding the security model and how to contact us with issues and questions. ### Attribution This vulnerability has been reported in [#46900](https://github.com/tensorflow/issues/46900) and fixed in [#46974](https://github.com/tensorflow/issues/46974).