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Severe, 6 weeks1496Projects326

1496 severe, 6 weeks · 326 projects

TensorFlowGHSA-vq2r-5xvm-3hc3

Segfault in `CTCBeamSearchDecoder`

TensorFlow

CVE-2021-29581 · Published May 21, 2021 · updated Jul 8, 2026

Low2.5
Fix: upgrade to 2.1.4 or later (4 fixed versions below)
GitHub advisory

Impact

Due to lack of validation in tf.raw_ops.CTCBeamSearchDecoder, an attacker can trigger denial of service via segmentation faults:

```python

import tensorflow as tf

inputs = tf.constant([], shape=[18, 8, 0], dtype=tf.float32)

sequence_length = tf.constant([11, -43, -92, 11, -89, -83, -35, -100],

shape=[8], dtype=tf.int32)

beam_width = 10

top_paths = 3

merge_repeated = True

tf.raw_ops.CTCBeamSearchDecoder(

inputs=inputs, sequence_length=sequence_length, beam_width=beam_width,

top_paths=top_paths, merge_repeated=merge_repeated)

`

The [implementation](https://github.com/tensorflow/tensorflow/blob/a74768f8e4efbda4def9f16ee7e13cf3922ac5f7/tensorflow/core/kernels/ctc_decoder_ops.cc#L68-L79) fails to detect cases when the input tensor is empty and proceeds to read data from a null buffer.

Patches

We have patched the issue in GitHub commit [b1b323042264740c398140da32e93fb9c2c9f33e](https://github.com/tensorflow/tensorflow/commit/b1b323042264740c398140da32e93fb9c2c9f33e).

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...

Affected versions

PackageAffectedFixed in
tensorflow
PyPI
< 2.1.42.1.4
>= 2.2.0, < 2.2.32.2.3
>= 2.3.0, < 2.3.32.3.3
>= 2.4.0, < 2.4.22.4.2
Details and references

### Impact Due to lack of validation in `tf.raw_ops.CTCBeamSearchDecoder`, an attacker can trigger denial of service via segmentation faults: ```python import tensorflow as tf inputs = tf.constant([], shape=[18, 8, 0], dtype=tf.float32) sequence_length = tf.constant([11, -43, -92, 11, -89, -83, -35, -100], shape=[8], dtype=tf.int32) beam_width = 10 top_paths = 3 merge_repeated = True tf.raw_ops.CTCBeamSearchDecoder( inputs=inputs, sequence_length=sequence_length, beam_width=beam_width, top_paths=top_paths, merge_repeated=merge_repeated) ``` The [implementation](https://github.com/tensorflow/tensorflow/blob/a74768f8e4efbda4def9f16ee7e13cf3922ac5f7/tensorflow/core/kernels/ctc_decoder_ops.cc#L68-L79) fails to detect cases when the input tensor is empty and proceeds to read data from a null buffer. ### Patches We have patched the issue in GitHub commit [b1b323042264740c398140da32e93fb9c2c9f33e](https://github.com/tensorflow/tensorflow/commit/b1b323042264740c398140da32e93fb9c2c9f33e). 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 by Yakun Zhang and Ying Wang of Baidu X-Team.

CVSS 3.1
CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:N/A:L
Severity from
GitHub (reviewed advisory)
Weakness
CWE-908
Also known as
BIT-tensorflow-2021-29581, CVE-2021-29581, PYSEC-2021-218, PYSEC-2021-509, PYSEC-2021-707

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