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CVE Record

CVE-2021-29557: Division by 0 in `SparseMatMul`

TensorFlow is an end-to-end open source platform for machine learning. An attacker can cause a denial of service via a FPE runtime error in `tf.raw_ops.SparseMatMul`. The division by 0 occurs deep in Eigen code because the `b` tensor is empty. 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-2021-29557 is a low-severity TensorFlow denial-of-service issue. A crafted condition involving an empty tensor can trigger a divide-by-zero runtime error in SparseMatMul, crashing the affected operation. It does not indicate data theft or code execution in the provided sources.

Executive priority

Schedule remediation through normal dependency maintenance unless SparseMatMul is exposed to untrusted users in a critical service. Prioritize higher if crashes could interrupt customer-facing ML workloads or shared compute environments.

Technical view

TensorFlow tf.raw_ops.SparseMatMul can reach Eigen code where an empty b tensor causes division by zero, producing a floating point exception. The source describes local, high-complexity, low-privilege exploitation with no confidentiality or integrity impact and low availability impact.

Likely exposure

Exposure is most likely in ML workloads, notebooks, containers, or services running affected TensorFlow versions and invoking SparseMatMul with user-influenced tensor inputs. The sources do not support broad remote exposure by default.

Exploitation context

The CVSS vector is local, high complexity, low privileges, and no user interaction. The source bundle does not identify active exploitation, and CISA KEV status is false. Treat this as a targeted availability risk in specific TensorFlow execution paths.

Researcher notes

The evidence supports CWE-369 division by zero and denial of service only. The provided fix reference is a TensorFlow commit, with patched releases named in the advisory text. Do not infer broader TensorFlow API impact beyond SparseMatMul from these sources.

Mitigation direction

  • Upgrade TensorFlow to 2.5.0 or a patched supported branch release.
  • Use 2.4.2, 2.3.3, 2.2.3, or 2.1.4 where those branches are required.
  • Restrict untrusted access to jobs or services that can reach SparseMatMul.
  • Check the TensorFlow advisory before rollout for branch-specific guidance.

Validation and detection

  • Inventory TensorFlow versions in production, notebooks, containers, and training images.
  • Identify workloads using tf.raw_ops.SparseMatMul or dependent sparse matrix operations.
  • Confirm deployed dependencies resolve to a patched TensorFlow release.
  • Retest affected ML workflows for availability after updating.
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-369: Exact CWE lookup

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cve · low confidence lookup

CVE-2021-29557 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-2021-29557Attack 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-369 · source CWE mapping

Divide By Zero

Divide By Zero represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.