CVE-2021-41221Public exploit

Heap buffer overflow via unchecked tensor ranks

Published Nov 5, 2021 · Updated Aug 4, 2024

Heap buffer overflow in TensorFlow before 2.4.4, 2.5.0 through 2.5.1, and 2.6.0 allows local users to access invalid memory. The CudnnRNN, CudnnRNNV2, and CudnnRNNV3 shape functions read dimensions from input, input_h, and input_c without first enforcing the ranks those dimension indexes require. Reachability requires local code to invoke a Cudnn operation with malformed-rank tensors; the advisory establishes invalid heap access but no specific post-overflow consequence.

CVSS severity7.8
High
EPSS probability0.22%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Heap buffer overflow in TensorFlow before 2.4.4, 2.5.0 through 2.5.1, and 2.6.0 allows local users to access invalid memory. The CudnnRNN, CudnnRNNV2, and CudnnRNNV3 shape functions read dimensions from input, input_h, and input_c without first enforcing the ranks those dimension indexes require. Reachability requires local code to invoke a Cudnn operation with malformed-rank tensors; the advisory establishes invalid heap access but no specific post-overflow consequence.

The record

CVE
CVE-2021-41221
Published
Nov 5, 2021
Updated
Aug 4, 2024
Vendor
Google
Product
TensorFlow
Classifications
CWE-787, CWE-120
Attack vector
local
Privileges
authenticated

Timeline

How it unfolded

  1. Nov 5, 2021CVE publishedPublication date reported by the CVE source.
  2. Aug 4, 2024Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=< 2.4.4
  2. Affected versionversion=>= 2.5.0, < 2.5.2
  3. Affected versionversion=>= 2.6.0, < 2.6.1

What conditions does exploitation require?

Attack vectorlocal
Required privilegesauthenticated

What is affected?

Google · TensorFlowversion=< 2.4.4; version=>= 2.5.0, < 2.5.2; version=>= 2.6.0, < 2.6.1

Published CVSS scores

7.8GitHub, Inc.CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
4.6NISTAV:L/AC:L/Au:N/C:P/I:P/A:P

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

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No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectorlocal
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-787Out-of-bounds Write
CWE-120Buffer Copy without Checking Size of Input ('Classic Buffer Overflow')

Public exploit references

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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