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CVE Record

CVE-2021-29580: Undefined behavior and `CHECK`-fail in `FractionalMaxPoolGrad`

TensorFlow is an end-to-end open source platform for machine learning. The implementation of `tf.raw_ops.FractionalMaxPoolGrad` triggers an undefined behavior if one of the input tensors is empty. The code is also vulnerable to a denial of service attack as a `CHECK` condition becomes false and aborts the process. The implementation(https://github.com/tensorflow/tensorflow/blob/169054888d50ce488dfde9ca55d91d6325efbd5b/tensorflow/core/kernels/fractional_max_pool_op.cc#L215) fails to validate that input and output tensors are not empty and are of the same rank. Each of these unchecked assumptions is responsible for the above issues. 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.

LowCVSS 2.5Not KEV-listedUpdated
Glexia's TakeAutomated analysislow

Security readout for executives and security teams

Plain-English summary

A malformed or empty tensor passed to TensorFlow's FractionalMaxPoolGrad can crash the process. The business impact is limited availability loss in workloads that run affected TensorFlow versions and process attacker-controlled or unreliable model inputs. It is not described as exposing data or changing results.

Executive priority

Treat as routine patching unless TensorFlow processes untrusted model inputs in shared or production services. The expected impact is process crash, not data theft or privilege escalation, based on provided sources.

Technical view

TensorFlow failed to validate that tensors supplied to tf.raw_ops.FractionalMaxPoolGrad were non-empty and same rank. Empty tensors can trigger undefined behavior, and a failed CHECK can abort the process. The vendor fix adds validation and was planned for TensorFlow 2.5.0 and patched supported maintenance releases.

Likely exposure

Exposure is likely limited to systems using affected TensorFlow versions and invoking FractionalMaxPoolGrad with inputs influenced by users, jobs, or model pipelines. Ordinary deployments that do not use this operation are less exposed.

Exploitation context

The source bundle does not show active exploitation, and KEV is false. CVSS indicates local access, high attack complexity, low privileges, no user interaction, and low availability impact only.

Researcher notes

The vulnerability is a missing validation issue in fractional_max_pool_op.cc. Evidence supports undefined behavior and process abort through failed assumptions about empty tensors and rank equality. No public exploit status is provided in the bundle.

Mitigation direction

  • Upgrade to TensorFlow 2.5.0 or a patched maintenance release named by the vendor.
  • For 2.4.x, use TensorFlow 2.4.2 or later within that branch.
  • For 2.3.x, use TensorFlow 2.3.3 or later within that branch.
  • For 2.2.x, use TensorFlow 2.2.3 or later within that branch.
  • For 2.1.x, use TensorFlow 2.1.4 or later within that branch.
  • Check TensorFlow vendor guidance if constrained to older unsupported versions.

Validation and detection

  • Inventory TensorFlow versions in applications, notebooks, training images, and inference containers.
  • Identify code paths using tf.raw_ops.FractionalMaxPoolGrad or models that may call it indirectly.
  • Confirm deployed artifacts no longer match the affected version ranges.
  • Review dependency lockfiles and base images for patched TensorFlow versions.
  • Run regression tests for ML workloads after upgrading TensorFlow.
Prepared
Confidence
high
Sources
4

Generated from the cited source records. This long-tail analysis has not been individually reviewed by a named human.

Potential ATT&CK relevance

Conservative CVE-to-ATT&CK context

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ATT&CK lookup starting points

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cwe · low confidence lookup

CWE-908: Exact CWE lookup

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cve · low confidence lookup

CVE-2021-29580 mapping review

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Vulnerability profileCVE Program record
Severity
Low
CVSS
2.5 (3.1)
Known Exploited
No
Published

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

Official CVE source material

CNA and ADP enrichment extracted from CVE v5

These fields come from the CVE record and ADP containers, not from Glexia's Take. They preserve time-varying source decisions such as CISA SSVC, KEV status, CVSS metrics, and provider references.

1CVSS vectors
0Timeline events
0ADP providers
3Source links

CVSS vector scores

1 official score

We collect every scored CVSS vector available in the official CNA and ADP containers. When more than one version is present, the table keeps the source vectors side by side instead of collapsing them into the highest score.

ScoreVersionSeverityVectorExploitImpactSource
2.5CVSS 3.1LowCVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:N/A:L11.4Primary CVE score

Vulnerability scoring details

Base CVSS 3.1 score

2.5Low
CVSS 3.1 vector shape for CVE-2021-29580Attack VectorAttack ComplexityPrivileges RequiredUser InteractionScopeConfidentiality ImpactIntegrity ImpactAvailability Impact

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

Attack Vector
NetworkAdjacentLocalPhysical
Attack Complexity
LowHigh
Privileges Required
NoneLowHigh
User Interaction
NoneRequired
Scope
ChangedUnchanged
Confidentiality Impact
HighLowNone
Integrity Impact
HighLowNone
Availability Impact
HighLowNone
Affected products

Products and packages named in the record

VendorProductVersion / packageStatus
tensorflowtensorflow< 2.1.4, >= 2.2.0, < 2.2.3, >= 2.3.0, < 2.3.3, >= 2.4.0, < 2.4.2Listed
Weakness

CWE details

CWE links open Glexia weakness intelligence pages with official CWE context, developer remediation guidance, and related CVE mappings.

CWE-908 · source CWE mapping

Use of Uninitialized Resource

Use of Uninitialized Resource represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.