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CVE Record

CVE-2021-29523: CHECK-fail in AddManySparseToTensorsMap

TensorFlow is an end-to-end open source platform for machine learning. An attacker can trigger a denial of service via a `CHECK`-fail in `tf.raw_ops.AddManySparseToTensorsMap`. This is because the implementation(https://github.com/tensorflow/tensorflow/blob/6f9896890c4c703ae0a0845394086e2e1e523299/tensorflow/core/kernels/sparse_tensors_map_ops.cc#L257) takes the values specified in `sparse_shape` as dimensions for the output shape. The `TensorShape` constructor(https://github.com/tensorflow/tensorflow/blob/6f9896890c4c703ae0a0845394086e2e1e523299/tensorflow/core/framework/tensor_shape.cc#L183-L188) uses a `CHECK` operation which triggers when `InitDims`(https://github.com/tensorflow/tensorflow/blob/6f9896890c4c703ae0a0845394086e2e1e523299/tensorflow/core/framework/tensor_shape.cc#L212-L296) returns a non-OK status. This is a legacy implementation of the constructor and operations should use `BuildTensorShapeBase` or `AddDimWithStatus` to prevent `CHECK`-failures in the presence of overflows. 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

This TensorFlow issue can let a user who can run TensorFlow operations crash a process through an internal assertion in a sparse tensor operation. The sourced impact is denial of service only; no confidentiality, integrity, privilege escalation, or active exploitation evidence is provided.

Executive priority

Handle through normal vulnerability remediation unless this runs in shared or customer-controlled ML execution environments. The business risk is service disruption, not data compromise, but exposed multi-tenant notebooks or inference systems deserve faster scheduling.

Technical view

CVE-2021-29523 is a CWE-190 overflow-related CHECK failure in tf.raw_ops.AddManySparseToTensorsMap. The implementation used sparse_shape values as output dimensions, and TensorShape construction could abort when dimension initialization failed. TensorFlow planned fixes in 2.5.0 and supported backports.

Likely exposure

Exposure is likely limited to TensorFlow deployments on affected versions: before 2.1.4, 2.2.0-2.2.2, 2.3.0-2.3.2, and 2.4.0-2.4.1. Risk is higher where untrusted users, notebooks, model code, or tensor inputs can reach raw TensorFlow operations.

Exploitation context

The CVSS vector is local, high complexity, low privileges required, no user interaction, and low availability impact. The source bundle says KEV is false, and the cited sources do not report active exploitation. Treat this as a process crash risk, not a remote takeover issue.

Researcher notes

The key condition is TensorShape construction from sparse_shape dimensions in AddManySparseToTensorsMap. The advisory attributes the failure to legacy CHECK-based construction and recommends safer shape-building APIs. Public evidence here is sufficient for version triage, but not for claiming exploitation in the wild.

Mitigation direction

  • Inventory TensorFlow versions in applications, notebooks, workers, containers, and ML pipelines.
  • Upgrade affected branches to TensorFlow 2.5.0 or patched supported backports.
  • Restrict untrusted users from executing arbitrary TensorFlow operations in shared environments.
  • Check TensorFlow vendor guidance before applying alternate mitigations.

Validation and detection

  • Confirm installed TensorFlow versions are not in the affected version ranges.
  • Review environments where tenant-controlled code or inputs can reach TensorFlow raw ops.
  • Verify dependency manifests and container images resolve to patched TensorFlow builds.
  • Confirm operational monitoring would detect TensorFlow worker crashes or restart loops.
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-190: Exact CWE lookup

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cve · low confidence lookup

CVE-2021-29523 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-2021-29523Attack 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-190 · source CWE mapping

Integer Overflow or Wraparound

Integer Overflow or Wraparound represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.