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CVE Record

CVE-2021-29566: Heap OOB access in `Dilation2DBackpropInput`

TensorFlow is an end-to-end open source platform for machine learning. An attacker can write outside the bounds of heap allocated arrays by passing invalid arguments to `tf.raw_ops.Dilation2DBackpropInput`. This is because the implementation(https://github.com/tensorflow/tensorflow/blob/afd954e65f15aea4d438d0a219136fc4a63a573d/tensorflow/core/kernels/dilation_ops.cc#L321-L322) does not validate before writing to the output array. The values for `h_out` and `w_out` are guaranteed to be in range for `out_backprop` (as they are loop indices bounded by the size of the array). However, there are no similar guarantees relating `h_in_max`/`w_in_max` and `in_backprop`. 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-2021-29566 is a low-severity TensorFlow memory safety bug. A user who can run TensorFlow operations locally could pass invalid arguments to Dilation2DBackpropInput and cause a heap out-of-bounds write. The published impact is limited to availability, with high attack complexity and required local privileges.

Executive priority

Treat as routine remediation unless TensorFlow runs in shared or semi-trusted ML environments. Prioritize normal patch cycles and dependency hygiene; escalate only where untrusted users can submit TensorFlow workloads.

Technical view

TensorFlow failed to validate input-derived indices before writing to the Dilation2DBackpropInput output buffer. h_out and w_out were bounded by out_backprop, but h_in_max and w_in_max were not similarly guaranteed for in_backprop. The issue is classified as CWE-787 with CVSS 3.1 score 2.5.

Likely exposure

Exposure is most relevant in environments running affected TensorFlow versions where untrusted or low-privileged users can execute TensorFlow code, jobs, notebooks, or model logic. Single-user controlled ML pipelines have lower practical exposure.

Exploitation context

The source bundle does not show KEV listing or active exploitation. Exploitation requires local access, low privileges, no user interaction, and high complexity. The documented security impact is availability loss, not confidentiality or integrity compromise.

Researcher notes

The bug is a heap out-of-bounds write in TensorFlow core kernel code for Dilation2DBackpropInput. The advisory names invalid arguments as the trigger condition, but the provided sources do not include exploitation evidence or broader product impact beyond TensorFlow.

Mitigation direction

  • Upgrade to TensorFlow 2.5.0 or a fixed supported patch release.
  • Use TensorFlow 2.4.2, 2.3.3, 2.2.3, or 2.1.4 where applicable.
  • Restrict untrusted users from executing arbitrary TensorFlow operations on shared systems.
  • Check current vendor guidance for unsupported TensorFlow versions.

Validation and detection

  • Inventory deployed TensorFlow versions in applications, notebooks, containers, and training images.
  • Compare versions against the affected ranges listed in the advisory.
  • Identify shared ML environments that permit untrusted TensorFlow code execution.
  • Confirm upgraded environments report a fixed TensorFlow release.
  • Review dependency lockfiles and container images for stale TensorFlow packages.
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-787: Exact CWE lookup

Use the exact CWE identifier as the starting point before reviewing related ATT&CK behavior. Open the exact CWE lookup page first, then review the ATT&CK searches from that MITRE weakness context. This is a Glexia lookup hint, not an official ATT&CK mapping.

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cve · low confidence lookup

CVE-2021-29566 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-2021-29566Attack 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-787 · source CWE mapping

Out-of-bounds Write

Out-of-bounds Write represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.