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CVE Record

CVE-2021-29540: Heap buffer overflow in `Conv2DBackpropFilter`

TensorFlow is an end-to-end open source platform for machine learning. An attacker can cause a heap buffer overflow to occur in `Conv2DBackpropFilter`. This is because the implementation(https://github.com/tensorflow/tensorflow/blob/1b0296c3b8dd9bd948f924aa8cd62f87dbb7c3da/tensorflow/core/kernels/conv_grad_filter_ops.cc#L495-L497) computes the size of the filter tensor but does not validate that it matches the number of elements in `filter_sizes`. Later, when reading/writing to this buffer, code uses the value computed here, instead of the number of elements in the tensor. 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-2021-29540 is a low-severity TensorFlow flaw in a convolution backpropagation operation. A local, low-privileged attacker who can run crafted TensorFlow workloads may trigger a heap buffer overflow and cause limited availability impact. The sources do not indicate data theft, integrity compromise, remote exploitation, or known active exploitation.

Executive priority

Treat this as routine patch management unless affected TensorFlow runs in shared or user-submitted workload environments. Business urgency is lower than internet-facing or data-exposure vulnerabilities, but outdated ML stacks should be upgraded during the next maintenance window.

Technical view

Conv2DBackpropFilter computes filter tensor size without validating it against the element count in filter_sizes. Later reads or writes use the computed size, creating a heap buffer overflow condition. Affected TensorFlow ranges include versions before 2.1.4, 2.2.x before 2.2.3, 2.3.x before 2.3.3, and 2.4.x before 2.4.2.

Likely exposure

Exposure is most likely in ML services, notebooks, CI jobs, or research systems running affected TensorFlow versions where local users or submitted workloads can execute TensorFlow operations. Purely static deployments without attacker-controlled model execution are less likely to be exposed.

Exploitation context

The CVSS vector requires local access, low privileges, no user interaction, high attack complexity, and indicates availability impact only. The provided sources mark KEV as false and do not report active exploitation or public weaponization.

Researcher notes

The key weakness is a size-validation mismatch in Conv2DBackpropFilter leading to heap buffer overflow. Evidence supports local, high-complexity availability risk only. The bundle does not provide exploit status beyond KEV false, and no additional affected products should be inferred.

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 branch pinning is required.
  • Inventory ML containers, notebooks, training workers, and CI images for TensorFlow versions.
  • Restrict untrusted users from running arbitrary TensorFlow workloads on shared systems.
  • Monitor the TensorFlow advisory for any later guidance.

Validation and detection

  • Confirm the TensorFlow version used by each application and runtime image.
  • Compare discovered versions with the affected ranges listed in the advisory.
  • Check dependency lockfiles, SBOMs, notebooks, and container build manifests.
  • Verify production and research environments are running patched versions.
  • Document any legacy unsupported TensorFlow usage for risk acceptance or upgrade planning.
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-120: Exact CWE lookup

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cve · low confidence lookup

CVE-2021-29540 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-2021-29540Attack 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-120 · source CWE mapping

Buffer Copy without Checking Size of Input ('Classic Buffer Overflow')

Buffer Copy without Checking Size of Input ('Classic Buffer Overflow') represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.