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CVE Record

CVE-2021-29556: Division by 0 in `Reverse`

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.Reverse`. This is because the implementation(https://github.com/tensorflow/tensorflow/blob/36229ea9e9451dac14a8b1f4711c435a1d84a594/tensorflow/core/kernels/reverse_op.cc#L75-L76) performs a division based on the first dimension of the tensor argument. 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 flaw can crash affected workloads when a user-controlled tensor reaches the Reverse operation. It affects availability only, not data confidentiality or integrity. The published severity is low because exploitation requires local access or a constrained path to influence TensorFlow inputs.

Executive priority

Treat as routine patch management unless affected TensorFlow workloads process untrusted inputs in shared or customer-facing environments. Business risk is limited to service disruption, but ML platforms with multi-user execution should remediate promptly.

Technical view

CVE-2021-29556 is a division-by-zero flaw in TensorFlow's tf.raw_ops.Reverse implementation. The vulnerable code divides using the tensor argument's first dimension, causing a floating point exception runtime error and denial of service under specific input conditions.

Likely exposure

Exposure is most likely in applications running affected TensorFlow versions and allowing untrusted users, plugins, or jobs to influence tensors processed by tf.raw_ops.Reverse. Sources do not identify broader affected products beyond TensorFlow.

Exploitation context

The CVSS vector is local, high complexity, low privileges, and availability-only impact. CISA KEV status is false in the supplied bundle, and no cited source states active exploitation.

Researcher notes

The evidence supports a narrow TensorFlow availability issue in tf.raw_ops.Reverse caused by division by zero. Do not assume remote exploitability from the sources. The commit reference is the authoritative code-level fix indicator; GHSA provides affected and patched release guidance.

Mitigation direction

  • Upgrade to TensorFlow 2.5.0 or later where the fix is included.
  • For supported older branches, apply TensorFlow 2.4.2, 2.3.3, 2.2.3, or 2.1.4.
  • Check TensorFlow advisory GHSA-fxqh-cfjm-fp93 before choosing a remediation path.
  • Restrict untrusted access to TensorFlow jobs that can submit arbitrary tensors.

Validation and detection

  • Inventory TensorFlow package versions across production, CI, notebooks, and model-serving containers.
  • Flag versions below 2.1.4, 2.2.3, 2.3.3, or 2.4.2 as applicable.
  • Confirm upgraded builds include TensorFlow 2.5.0 or the listed patched branch release.
  • Review services for user-controlled tensor inputs reaching Reverse operations.
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-369: Exact CWE lookup

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cve · low confidence lookup

CVE-2021-29556 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-2021-29556Attack 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.