# CVE-2021-42521: vtk9: There is a NULL pointer dereference vulnerability in VTK before 9.2.5, and it lies in IO/Infovis/vtkXMLTreeReader.cxx

CVE-2021-42521 is fixed in vtk9 on 1 platform, first by DEBIAN-CVE-2021-42521, released August 25, 2022. It is not reported as exploited. Patch Radar priority: High.

- Web page: https://patchblox.com/security/cve/CVE-2021-42521
- Priority: High
- CVSS: 7.5 (high)
- EPSS: 0.0132
- CISA KEV: not listed
- Exploited (vendor report): no
- Publicly disclosed: no
- Published: Aug 25, 2022

## Description

There is a NULL pointer dereference vulnerability in VTK before 9.2.5, and it lies in IO/Infovis/vtkXMLTreeReader.cxx. The vendor didn't check the return value of libxml2 API 'xmlDocGetRootElement', and try to dereference it. It is unsafe as the return value can be NULL and that NULL pointer dereference may crash the application.

## Where it's fixed

| Platform | Product | Fixed in | Fix | Released |
|---|---|---|---|---|
| Linux | vtk9 Debian 13.5 (trixie) | 9.1.0+really9.1.0+dfsg2-8 | [DEBIAN-CVE-2021-42521](https://patchblox.com/security/data/fix/linux/debian-cve-2021-42521.md) | Aug 25, 2022 |
| Linux | vtk9 Debian 14 | 9.1.0+really9.1.0+dfsg2-8 | [DEBIAN-CVE-2021-42521](https://patchblox.com/security/data/fix/linux/debian-cve-2021-42521.md) | Aug 25, 2022 |

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