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CVE Record

CVE-2021-29549: Division by 0 in `QuantizedAdd`

TensorFlow is an end-to-end open source platform for machine learning. An attacker can cause a runtime division by zero error and denial of service in `tf.raw_ops.QuantizedBatchNormWithGlobalNormalization`. This is because the implementation(https://github.com/tensorflow/tensorflow/blob/6f26b3f3418201479c264f2a02000880d8df151c/tensorflow/core/kernels/quantized_add_op.cc#L289-L295) computes a modulo operation without validating that the divisor is not zero. Since `vector_num_elements` is determined based on input shapes(https://github.com/tensorflow/tensorflow/blob/6f26b3f3418201479c264f2a02000880d8df151c/tensorflow/core/kernels/quantized_add_op.cc#L522-L544), a user can trigger scenarios where this quantity is 0. 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 is a low-severity TensorFlow denial-of-service issue. A local, low-privileged attacker who can influence affected TensorFlow inputs may trigger a division-by-zero runtime error, disrupting availability. The sources do not indicate data theft, privilege escalation, remote exploitation, or active exploitation.

Executive priority

Treat as routine patching unless affected TensorFlow services are multi-tenant or accept untrusted ML workloads. The business impact is availability disruption, not confirmed data compromise.

Technical view

Affected TensorFlow code performs a modulo operation without first ensuring the divisor is nonzero. Because vector_num_elements is derived from input shapes, certain shapes can make it zero and trigger a division-by-zero failure. The advisory states fixes are in TensorFlow 2.5.0 and backported supported releases.

Likely exposure

Exposure is mainly TensorFlow deployments using affected versions: before 2.1.4, 2.2.0 before 2.2.3, 2.3.0 before 2.3.3, or 2.4.0 before 2.4.2, where low-privileged users can influence relevant inputs.

Exploitation context

The CVSS vector indicates local access, high attack complexity, low privileges, no user interaction, and low availability impact. CISA KEV status is false in the bundle, and no cited source supports active exploitation.

Researcher notes

The bundle title references QuantizedAdd, while the description names tf.raw_ops.QuantizedBatchNormWithGlobalNormalization and links quantized_add_op.cc. Validate the exact affected path against the GitHub advisory and commit before writing detections.

Mitigation direction

  • Upgrade TensorFlow to 2.5.0 or a fixed backport release.
  • Use TensorFlow 2.4.2, 2.3.3, 2.2.3, or 2.1.4 where applicable.
  • Limit untrusted users from submitting TensorFlow graphs or inputs until fixed.
  • Check TensorFlow advisory guidance for supported upgrade paths.

Validation and detection

  • Inventory TensorFlow versions across applications, notebooks, containers, and ML workers.
  • Confirm deployed versions are outside the affected ranges listed in the advisory.
  • Identify services where untrusted users influence TensorFlow input shapes or graphs.
  • Retest availability-sensitive ML workflows after upgrading TensorFlow.
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-2021-29549 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-2021-29549Attack 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.