AVID-2026-R0733

Description

Segfault in SparseCountSparseOutput (CVE-2021-29521)

Details

TensorFlow is an end-to-end open source platform for machine learning. Specifying a negative dense shape in tf.raw_ops.SparseCountSparseOutput results in a segmentation fault being thrown out from the standard library as std::vector invariants are broken. This is because the implementation(https://github.com/tensorflow/tensorflow/blob/8f7b60ee8c0206a2c99802e3a4d1bb55d2bc0624/tensorflow/core/kernels/count_ops.cc#L199-L213) assumes the first element of the dense shape is always positive and uses it to initialize a BatchedMap<T> (i.e., std::vector<absl::flat_hash_map<int64,T>>(https://github.com/tensorflow/tensorflow/blob/8f7b60ee8c0206a2c99802e3a4d1bb55d2bc0624/tensorflow/core/kernels/count_ops.cc#L27)) data structure. If the shape tensor has more than one element, num_batches is the first value in shape. Ensuring that the dense_shape argument is a valid tensor shape (that is, all elements are non-negative) solves this issue. The fix will be included in TensorFlow 2.5.0. We will also cherrypick this commit on TensorFlow 2.4.2 and TensorFlow 2.3.3.

Reason for inclusion in AVID: CVE-2021-29521 describes a segmentation fault caused by a negative dense_shape in TensorFlow’s SparseCountSparseOutput. TensorFlow is a core AI framework used in ML pipelines, so this is a software vulnerability in a component that is part of the software stack for general-purpose AI systems. The advisory and CVE entry provide the vulnerability and fix details, indicating it affects the software supply chain (dependencies/runtimes used to build/run AI systems).

References

Affected or Relevant Artifacts

Developer: tensorflow
Deployer: tensorflow
Artifact Details:

Type	Name
System	tensorflow

Impact

AVID Taxonomy Categorization

Risk domains: Security
SEP subcategories: S0100: Software Vulnerability
Lifecycle stages: L06: Deployment

CVSS

Version	3.1
Vector String	CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:N/A:L
Base Score	2.5
Base Severity	🟢 Low
Attack Vector	LOCAL
Attack Complexity	🔴 High
Privileges Required	🟢 Low
User Interaction	NONE
Scope	UNCHANGED
Confidentiality Impact	NONE
Integrity Impact	NONE
Availability Impact	🟢 Low

CWE

ID	Description
CWE-131	CWE-131: Incorrect Calculation of Buffer Size

Other information

Report Type: Advisory
Credits:
Date Reported: 2021-05-14
Version: 0.3.3
AVID Entry