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CVE Record

CVE-2021-29555: Division by 0 in `FusedBatchNorm`

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.FusedBatchNorm`. This is because the implementation(https://github.com/tensorflow/tensorflow/blob/828f346274841fa7505f7020e88ca36c22e557ab/tensorflow/core/kernels/fused_batch_norm_op.cc#L295-L297) performs a division based on the last dimension of the `x` tensor. Since this is controlled by the user, an attacker can trigger a denial of service. 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-2021-29555 is a low-severity TensorFlow denial-of-service issue. If an attacker can influence inputs to a vulnerable FusedBatchNorm operation, TensorFlow can hit a divide-by-zero runtime error and stop the affected process. The sources do not indicate data theft, integrity impact, or active exploitation.

Executive priority

Treat as a routine dependency update unless TensorFlow is exposed to untrusted ML inputs in production. Business risk is service disruption, not compromise of data or control.

Technical view

TensorFlow tf.raw_ops.FusedBatchNorm can trigger a floating-point exception because the implementation divides using the last dimension of the x tensor, which user input can control. The issue is CWE-369 and affects specified TensorFlow 2.1.x through 2.4.x ranges before patched releases.

Likely exposure

Exposure is most likely in applications running affected TensorFlow versions and accepting untrusted models, graphs, or tensor shapes that reach FusedBatchNorm. Internal-only ML workflows with trusted inputs have lower practical risk.

Exploitation context

The CVSS vector requires local access, low privileges, high attack complexity, and no user interaction. KEV status is false, and the provided sources do not report active exploitation. Impact is limited to low availability loss.

Researcher notes

The root cause is a divide-by-zero condition in FusedBatchNorm tied to tensor shape handling. The public bundle names the fixing release branches but does not provide evidence of exploitation in the wild.

Mitigation direction

  • Upgrade TensorFlow to 2.5.0 or a patched supported branch release.
  • Use TensorFlow 2.4.2, 2.3.3, 2.2.3, or 2.1.4 where applicable.
  • Prioritize services that process untrusted ML inputs or user-controlled tensor shapes.
  • Check TensorFlow advisory guidance before relying on compensating controls.

Validation and detection

  • Inventory TensorFlow versions across applications, containers, and notebooks.
  • Compare installed versions against the affected ranges in the CVE source bundle.
  • Identify code paths using FusedBatchNorm with externally influenced inputs.
  • Confirm upgraded environments use a fixed TensorFlow release.
  • Review application monitoring for unexplained TensorFlow process crashes.
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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Open ATT&CK lookup
cve · low confidence lookup

CVE-2021-29555 mapping review

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Open ATT&CK lookup
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-2021-29555Attack 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.