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CVE Record

CVE-2021-37666: Reference binding to nullptr in `RaggedTensorToVariant` in TensorFlow

TensorFlow is an end-to-end open source platform for machine learning. In affected versions an attacker can cause undefined behavior via binding a reference to null pointer in `tf.raw_ops.RaggedTensorToVariant`. The [implementation](https://github.com/tensorflow/tensorflow/blob/460e000de3a83278fb00b61a16d161b1964f15f4/tensorflow/core/kernels/ragged_tensor_to_variant_op.cc#L129) has an incomplete validation of the splits values, missing the case when the argument would be empty. We have patched the issue in GitHub commit be7a4de6adfbd303ce08be4332554dff70362612. The fix will be included in TensorFlow 2.6.0. We will also cherrypick this commit on TensorFlow 2.5.1, TensorFlow 2.4.3, and TensorFlow 2.3.4, as these are also affected and still in supported range.

HighCVSS 7.8Not KEV-listedUpdated
Glexia's TakeAutomated analysishigh

Security readout for executives and security teams

Plain-English summary

Affected TensorFlow versions mishandle an empty input case in a ragged tensor conversion operation. A user who can run TensorFlow code locally could trigger undefined behavior, with high confidentiality, integrity, and availability impact per CVSS. This matters most in shared ML platforms and notebooks.

Executive priority

Treat as high priority for shared or multi-user ML infrastructure. The issue is patched and version-bounded, so remediation should focus on upgrading affected TensorFlow deployments and limiting untrusted code execution until patched.

Technical view

`tf.raw_ops.RaggedTensorToVariant` missed validation for empty splits values, leading to a reference binding to a null pointer. TensorFlow patched this in commit `be7a4de6adfbd303ce08be4332554dff70362612`, with fixes planned for 2.6.0, 2.5.1, 2.4.3, and 2.3.4.

Likely exposure

Exposure is likely where TensorFlow is installed in affected ranges and low-privileged users can execute TensorFlow operations. This includes shared training hosts, notebooks, CI jobs, or ML services that pass untrusted requests into TensorFlow execution paths.

Exploitation context

The source bundle does not report active exploitation, and CISA KEV status is false. CVSS indicates local attack vector, low complexity, low privileges, and no user interaction. No remote exploit path is established by the provided sources.

Researcher notes

This is CWE-824: access or binding involving a null pointer. The advisory attributes the bug to incomplete splits validation in `RaggedTensorToVariant`, specifically missing the empty-argument case. Provided sources do not include proof-of-concept details or exploitation claims.

Mitigation direction

  • Upgrade TensorFlow to 2.6.0 or later where possible.
  • For supported branches, apply 2.5.1, 2.4.3, or 2.3.4 fixes.
  • Restrict untrusted users from running arbitrary TensorFlow operations on shared systems.
  • Review vendor advisory and commit for branch-specific patch availability.
  • Prioritize shared ML environments before isolated developer workstations.

Validation and detection

  • Inventory TensorFlow package versions across hosts, containers, notebooks, and CI images.
  • Flag versions >=2.5.0 <2.5.1, >=2.4.0 <2.4.3, and <2.3.4.
  • Check whether workloads expose ragged tensor conversion to untrusted users or jobs.
  • Confirm patched versions are deployed in runtime images, not only build manifests.
  • Document any unavoidable affected deployments and compensating access controls.
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-824: Exact CWE lookup

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cve · low confidence lookup

CVE-2021-37666 mapping review

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Vulnerability profileCVE Program record
Severity
High
CVSS
7.8 (3.1)
Known Exploited
No
Published

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

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
7.8CVSS 3.1HighCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H1.85.9Primary CVE score

Vulnerability scoring details

Base CVSS 3.1 score

7.8High
CVSS 3.1 vector shape for CVE-2021-37666Attack VectorAttack ComplexityPrivileges RequiredUser InteractionScopeConfidentiality ImpactIntegrity ImpactAvailability Impact

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

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>= 2.5.0, < 2.5.1, >= 2.4.0, < 2.4.3, < 2.3.4Listed
Weakness

CWE details

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

CWE-824 · source CWE mapping

Access of Uninitialized Pointer

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