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

> An attacker can crash applications using Qt SVG by providing a crafted SVG image that triggers a type confusion and heap overflow.

- **Severity:** High 8.7 (`CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 6 May 2026
- **Updated:** 29 Jul 2026
- **Also known as:** DEBIAN-CVE-2026-6210, GHSA-mh4x-qpf6-hr3q, UBUNTU-CVE-2026-6210, openSUSE-SU-2026:10742-1

## What is CVE-2026-6210?

CVE-2026-6210 is a high-severity memory corruption vulnerability in Qt, published on 6 May 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official 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.

Weakness: CWE-843 (Access of Resource Using Incompatible Type), CWE-122 (Heap-based Buffer Overflow)

## Which versions are affected by CVE-2026-6210?


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `qt6-svg` | openSUSE:Tumbleweed | All versions | 6.11.0-2.1 |

## How do I fix CVE-2026-6210?

Upgrade to a fixed version.

## Is CVE-2026-6210 being exploited?

There is no known exploitation of CVE-2026-6210 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-6210 and fix it if it is affected.

What it is: CVE-2026-6210 is a high-severity memory corruption vulnerability in Qt, published on 6 May 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2026-6210 in the wild and no public exploit code.

Affected product: Qt. No package-level version data is available, so check the vendor advisory linked from the reference page.

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2026-6210/ (Markdown: https://insights.sbomify.com/CVE-2026-6210/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-6210
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-6210
- OSV: https://osv.dev/vulnerability/CVE-2026-6210

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-6210/
Summaries are generated and may contain mistakes; the official description above is the record.