CVE-2026-34445Network attack vector

Service crash via unchecked external-data attributes

Published Apr 1, 2026 · Updated Apr 1, 2026

Improper input validation in ONNX before 1.21.0 allows remote attackers to crash model-loading services via crafted model files. ExternalDataInfo.init passes arbitrary external_data keys to setattr(), while load paths accept unchecked offset and length values. Exploitation requires a service to load an attacker-supplied model; oversized lengths can exhaust memory, while negative bounds cause unintended reads or errors.

CVSS severity8.6
High
EPSS probability0.29%
Next 30 days · Sep 17, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Improper input validation in ONNX before 1.21.0 allows remote attackers to crash model-loading services via crafted model files. ExternalDataInfo.init passes arbitrary external_data keys to setattr(), while load paths accept unchecked offset and length values. Exploitation requires a service to load an attacker-supplied model; oversized lengths can exhaust memory, while negative bounds cause unintended reads or errors.

The record

CVE
CVE-2026-34445
Published
Apr 1, 2026
Updated
Apr 1, 2026
Vendor
ONNX
Product
ONNX
Classifications
CWE-20, CWE-400, CWE-915, T1499.004
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Apr 1, 2026CVE publishedPublication date reported by the CVE source.
  2. Apr 1, 2026Record 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=< 1.21.0

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

ONNX · ONNXversion=< 1.21.0

Published CVSS scores

8.6GitHub, Inc.CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:H

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)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-20Improper Input Validation
CWE-400Uncontrolled Resource Consumption
CWE-915Improperly Controlled Modification of Dynamically-Determined Object Attributes
T1499.004Endpoint Denial of Service: Application or System Exploitation

Public exploit references

No public exploit references are available in this record.

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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