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CVE Record

CVE-2021-29616: Null dereference in Grappler's `TrySimplify`

TensorFlow is an end-to-end open source platform for machine learning. The implementation of TrySimplify(https://github.com/tensorflow/tensorflow/blob/c22d88d6ff33031aa113e48aa3fc9aa74ed79595/tensorflow/core/grappler/optimizers/arithmetic_optimizer.cc#L390-L401) has undefined behavior due to dereferencing a null pointer in corner cases that result in optimizing a node with no inputs. 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

CVE-2021-29616 is a low-severity TensorFlow bug that can cause a process crash in limited circumstances. The issue is a null pointer dereference in Grappler optimization when handling a node with no inputs. Business urgency is low unless affected TensorFlow versions process untrusted or externally supplied ML graphs or models.

Executive priority

Schedule remediation through normal patch management unless TensorFlow is exposed to untrusted model inputs. The expected impact is service instability or job failure, not compromise of sensitive data. Track completion because patched versions are available from the vendor.

Technical view

TensorFlow Grappler's arithmetic optimizer function TrySimplify can dereference a null pointer in corner cases involving optimization of a node with no inputs. The CVSS 3.1 vector is local, high complexity, low privilege, no confidentiality or integrity impact, and low availability impact.

Likely exposure

Exposure is limited to TensorFlow deployments using affected versions: before 2.1.4, 2.2.x before 2.2.3, 2.3.x before 2.3.3, and 2.4.x before 2.4.2. Risk is most relevant where TensorFlow optimizes graphs or models not fully controlled by the organization.

Exploitation context

The provided sources do not report active exploitation, and the CVE is not listed as KEV. The CVSS vector indicates local access, high attack complexity, and low availability impact. Treat this as a crash risk rather than a data theft or privilege escalation issue.

Researcher notes

The evidence points to CWE-476 null pointer dereference in TensorFlow Grappler TrySimplify. Public sources identify affected version ranges and fixed release targets, but do not provide evidence of exploitation in the wild. Avoid assuming remote exploitability beyond the CVSS local attack vector.

Mitigation direction

  • Upgrade TensorFlow to 2.5.0 or later where practical.
  • For supported older branches, apply TensorFlow 2.4.2, 2.3.3, 2.2.3, or 2.1.4.
  • Prioritize systems that process external or user-supplied TensorFlow graphs or models.
  • Check TensorFlow's advisory before using unsupported versions or custom forks.

Validation and detection

  • Inventory TensorFlow versions across application, notebook, CI, and ML serving environments.
  • Confirm no runtime uses the affected version ranges listed in the advisory.
  • Review whether services accept externally supplied TensorFlow graphs or models.
  • After upgrade, run existing ML workload and regression tests for compatibility.
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

These mappings and lookup hints may be relevant to the vulnerability behavior, CWE, affected product, or exposure path. Glexia-inferred context is not an official MITRE, ATT&CK, CWE, or CVE Program mapping.

ATT&CK lookup starting points

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cwe · low confidence lookup

CWE-476: Exact CWE lookup

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cve · low confidence lookup

CVE-2021-29616 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-2021-29616Attack 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-476 · source CWE mapping

NULL Pointer Dereference

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