2.5

CVSS Score

3.1

Basic Information

CVE ID

CVE-2021-29543

GHSA ID

GHSA-fphq-gw9m-ghrv

EPSS Score

0.01803%

CWE

CWE-617

Published

5/21/2021

Updated

10/31/2024

KEV Status

Technology

Python

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CVE-2021-29543

CVE-2021-29543:
CHECK-fail in `CTCGreedyDecoder`

Impact

An attacker can trigger a denial of service via a CHECK-fail in tf.raw_ops.CTCGreedyDecoder:

import tensorflow as tf

inputs = tf.constant([], shape=[18, 2, 0], dtype=tf.float32)
sequence_length = tf.constant([-100, 17], shape=[2], dtype=tf.int32)
merge_repeated = False

tf.raw_ops.CTCGreedyDecoder(inputs=inputs, sequence_length=sequence_length, merge_repeated=merge_repeated)

This is because the implementation 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.

Patches

We have patched the issue in GitHub commit ea3b43e98c32c97b35d52b4c66f9107452ca8fb2.

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 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.

(GitHub Advisory)

2.5

CVSS Score

3.1

Basic Information

CVE ID

CVE-2021-29543

GHSA ID

GHSA-fphq-gw9m-ghrv

EPSS Score

0.01803%

CWE

CWE-617

Published

5/21/2021

Updated

10/31/2024

KEV Status

Technology

Python

Technical Details

CVSS Vector

CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:N/A:L

Package Name	Ecosystem	Vulnerable Versions	First Patched Version
tensorflow	pip	< 2.1.4	2.1.4
tensorflow	pip	>= 2.2.0, < 2.2.3	2.2.3
tensorflow	pip	>= 2.3.0, < 2.3.3	2.3.3
tensorflow	pip	>= 2.4.0, < 2.4.2	2.4.2
tensorflow-cpu	pip	< 2.1.4	2.1.4
tensorflow-cpu	pip	>= 2.2.0, < 2.2.3	2.2.3
tensorflow-cpu	pip	>= 2.3.0, < 2.3.3	2.3.3
tensorflow-cpu	pip	>= 2.4.0, < 2.4.2	2.4.2
tensorflow-gpu	pip	< 2.1.4	2.1.4
tensorflow-gpu	pip	>= 2.2.0, < 2.2.3	2.2.3
tensorflow-gpu	pip	>= 2.3.0, < 2.3.3	2.3.3
tensorflow-gpu	pip	>= 2.4.0, < 2.4.2	2.4.2

Vulnerability Intelligence
Miggo AI

Root Cause Analysis

The vulnerability stems from the original implementation in CTCGreedyDecoderOp::Compute where a CHECK_LT assertion was used to validate indices without prior input validation. The provided exploit uses an input with shape [18, 2, 0], causing dimension(1) to be 0. The loop in Compute attempts to access input_list_t[t] without checking if dimension(1) > 0 first, leading to a CHECK failure. The patch adds an OP_REQUIRES check for this condition, confirming this as the vulnerable code path.

Vulnerable functions

Only Mi**o us*rs **n s** t*is s**tion

WAF Protection Rules

WAF Rule

### Imp**t *n *tt**k*r **n tri***r * **ni*l o* s*rvi** vi* * `****K`-**il in `t*.r*w_ops.*T**r***y***o**r`: ```pyt*on import t*nsor*low *s t* inputs = t*.*onst*nt([], s**p*=[**, *, *], *typ*=t*.*lo*t**) s*qu*n**_l*n*t* = t*.*onst*nt([-***, **], s**

Reasoning

T** vuln*r**ility st*ms *rom t** ori*in*l impl*m*nt*tion in *T**r***y***o**rOp::*omput* w**r* * ****K_LT *ss*rtion w*s us** to v*li**t* in*i**s wit*out prior input v*li**tion. T** provi*** *xploit us*s *n input wit* s**p* [**, *, *], **usin* *im*nsio

2.5

Basic Information

Concerned about an active attack path?

CVE-2021-29543: CHECK-fail in `CTCGreedyDecoder`

Impact

Patches

For more information

Attribution

2.5

Basic Information

Technical Details

Vulnerability IntelligenceMiggo AI

Root Cause Analysis

Vulnerable functions

WAF Protection Rules

WAF Rule

Reasoning

CVE-2021-29543:
CHECK-fail in `CTCGreedyDecoder`

Vulnerability Intelligence
Miggo AI