# CVE-2026-6210: Type confusion and heap-buffer-overflow in Qt SVG marker handling causing application crash

CVE-2026-6210 is fixed in 6 products on 1 platform, first by DEBIAN-CVE-2026-6210, released May 15, 2026. It is not reported as exploited. Patch Radar priority: High.

- Web page: https://patchblox.com/security/cve/CVE-2026-6210
- Priority: High
- CVSS: n/a (Important)
- EPSS: 0.0028
- CISA KEV: not listed
- Exploited (vendor report): no
- Publicly disclosed: no
- Published: May 6, 2026
- Weakness: Access of Resource Using Incompatible Type ('Type Confusion')
- Vendor advisory: https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-6210

## Description

A type confusion vulnerability in Qt SVG allows an attacker to cause an application crash via a crafted SVG image.    When processing SVG marker references, the renderer retrieves a node by its id attribute and casts it to QSvgMarker* without verifying the node type. A non-marker element (such as a <line> element) that references itself as a marker triggers an out-of-bounds heap read due to the object size difference between QSvgLine and QSvgMarker,  followed by an endless recursion that bypasses the marker recursion  guard through incorrect virtual dispatch. The result is an application  crash (denial of service).    This issue affects Qt SVG:  from 6.7.0 before 6.8.8, from 6.9.0 before 6.11.1.

## Where it's fixed

| Platform | Product | Fixed in | Fix | Released |
|---|---|---|---|---|
| Linux | mingw-qt6-qtsvg Fedora 43 | 6.10.3-2.fc43 | [FEDORA-2026-B63645CAD6](https://patchblox.com/security/data/fix/linux/fedora-2026-b63645cad6.md) | May 20, 2026 |
| Linux | mingw32-qt6-qtsvg Fedora 43 | 6.10.3-2.fc43 | [FEDORA-2026-B63645CAD6](https://patchblox.com/security/data/fix/linux/fedora-2026-b63645cad6.md) | May 20, 2026 |
| Linux | mingw32-qt6-qtsvg-debuginfo Fedora 43 | 6.10.3-2.fc43 | [FEDORA-2026-B63645CAD6](https://patchblox.com/security/data/fix/linux/fedora-2026-b63645cad6.md) | May 20, 2026 |
| Linux | mingw64-qt6-qtsvg Fedora 43 | 6.10.3-2.fc43 | [FEDORA-2026-B63645CAD6](https://patchblox.com/security/data/fix/linux/fedora-2026-b63645cad6.md) | May 20, 2026 |
| Linux | mingw64-qt6-qtsvg-debuginfo Fedora 43 | 6.10.3-2.fc43 | [FEDORA-2026-B63645CAD6](https://patchblox.com/security/data/fix/linux/fedora-2026-b63645cad6.md) | May 20, 2026 |
| Linux | qt6-svg Debian 14 | 6.10.2-6 | [DEBIAN-CVE-2026-6210](https://patchblox.com/security/data/fix/linux/debian-cve-2026-6210.md) | May 15, 2026 |

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Data as of 2026-11-08T13:06:02Z UTC. Source: Patchblox Patch Radar (https://patchblox.com/security/patch-radar). Patchblox finds out-of-date software on Windows, macOS and Linux and updates it through release rings: https://patchblox.com/demo

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