# CVE-2026-78253: Denial-of-service (stack-exhaustion) vulnerability in QXmlStreamReader::readElementText() impacts Qt

> Attackers can crash applications using Qt's XML reader by sending crafted XML documents that cause stack exhaustion.

- **Severity:** Low 2.3 (`CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:P/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:U/S:N/AU:N/R:U/RE:L/U:Green`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** A user has to click or open something
- **Fix available:** Yes
- **Published:** 23 Sep 2026
- **Updated:** 23 Sep 2026
- **Also known as:** AZL-106827, DEBIAN-CVE-2026-78253, ECHO-abe8-219d-6f61, GHSA-cpqc-q57w-7c2q, UBUNTU-CVE-2026-78253

## What is CVE-2026-78253?

CVE-2026-78253 is a low-severity denial of service vulnerability in qt, published on 23 Sep 2026. An attacker can exploit it over the internet without logging in, and only if a user opens a file or follows a link.

### Official description

Uncontrolled recursion in QXmlStreamReader::readElementText() in Qt Group Qt allows attackers to cause a denial of service (application crash via stack exhaustion) via a crafted XML document.

Weakness: CWE-674 (Uncontrolled Recursion)

## Which versions are affected by CVE-2026-78253?


## How do I fix CVE-2026-78253?

Apply the vendor's patch.

## Is CVE-2026-78253 being exploited?

There is no known exploitation of CVE-2026-78253 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-78253 and fix it if it is affected.

What it is: CVE-2026-78253 is a low-severity denial of service vulnerability in qt, published on 23 Sep 2026. An attacker can exploit it over the internet without logging in, and only if a user opens a file or follows a link.
Exploitation: There is no known exploitation of CVE-2026-78253 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-2026-78253/ (Markdown: https://insights.sbomify.com/CVE-2026-78253/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-78253
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-78253
- OSV: https://osv.dev/vulnerability/CVE-2026-78253

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-78253/
Summaries are generated and may contain mistakes; the official description above is the record.