CVE-2021-42521Network attack vector

Application crash via unchecked XML root

Published Aug 25, 2022 · Updated Aug 4, 2024

NULL pointer dereference in Kitware VTK before 9.2.5 allows remote attackers to crash applications via a malformed XML tree. In vtkXMLTreeReader::RequestData, xmlDocGetRootElement can return null, but the result is passed to vtkXMLTreeReaderProcessElement without a null check. The embedding application must parse attacker-controlled XML with vtkXMLTreeReader; exploitation terminates that process without reading or changing data.

CVSS severity7.5
High
EPSS probability1.29%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

NULL pointer dereference in Kitware VTK before 9.2.5 allows remote attackers to crash applications via a malformed XML tree. In vtkXMLTreeReader::RequestData, xmlDocGetRootElement can return null, but the result is passed to vtkXMLTreeReaderProcessElement without a null check. The embedding application must parse attacker-controlled XML with vtkXMLTreeReader; exploitation terminates that process without reading or changing data.

The record

CVE
CVE-2021-42521
Published
Aug 25, 2022
Updated
Aug 4, 2024
Vendor
Kitware
Product
VTK
Classifications
CWE-400, CWE-476, T1499
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Aug 25, 2022CVE 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=VTK - 9.0.0 and before

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Kitware · VTKversion=VTK - 9.0.0 and before

Published CVSS scores

7.5NIST NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/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-400Uncontrolled Resource Consumption
CWE-476NULL Pointer Dereference
T1499Endpoint Denial of Service

Public exploit references

No public exploit references are available in this record.

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Technologies

Your stack

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Your stack

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