# CVE-2026-76151: Denial of service in qt

> Remote attackers can crash applications using QtNetwork by sending oversized Cache-Control headers, causing a denial of service.

- **Severity:** Medium 4.6 (`CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:U/AU:N/R:A`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 16 Sep 2026
- **Updated:** 16 Sep 2026
- **Also known as:** DEBIAN-CVE-2026-76151, ECHO-1632-1dd1-3803, GHSA-32mm-x94q-6h38, UBUNTU-CVE-2026-76151

## What is CVE-2026-76151?

CVE-2026-76151 is a medium-severity denial of service vulnerability in qt, published on 16 Sep 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

Out-of-bounds read (buffer over-read) in the HTTP Cache-Control response header parsing in the QtNetwork module in Qt Group Qt 6.0.0 through 6.8.8, and 6.9.0 through 6.11.1, allows remote attackers to cause a denial of service (application crash) via an excessively large Cache-Control header value returned by an untrusted or compromised HTTP server to an application using QNetworkAccessManager. Only the client side of the connection is affected and 32-bit builds are not affected; the out-of-bounds access is read-only, with no information disclosure and no code execution.

Weakness: CWE-197 (Numeric Truncation Error), CWE-125 (Out-of-bounds Read)

## Which versions are affected by CVE-2026-76151?


## How do I fix CVE-2026-76151?

Apply the vendor's patch.

## Is CVE-2026-76151 being exploited?

There is no known exploitation of CVE-2026-76151 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-76151 and fix it if it is affected.

What it is: CVE-2026-76151 is a medium-severity denial of service vulnerability in qt, published on 16 Sep 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-2026-76151 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-2026-76151/ (Markdown: https://insights.sbomify.com/CVE-2026-76151/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-76151
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-76151
- OSV: https://osv.dev/vulnerability/CVE-2026-76151

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-76151/
Summaries are generated and may contain mistakes; the official description above is the record.