# CVE-2026-11352: QUIC zero-length UDP datagrams busy-loop

> A malicious HTTP/3 server can cause a remote denial of service against curl clients by streaming zero-length UDP datagrams, stalling the QUIC receive loop.

- **Severity:** High 7.5 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 3 Jul 2026
- **Updated:** 15 Sep 2026
- **Also known as:** ALPINE-CVE-2026-11352, BELL-CVE-2026-11352, CURL-CVE-2026-11352, DEBIAN-CVE-2026-11352, GHSA-qxwx-hr5v-h5q4, JLSEC-2026-1198, MINI-2gg7-7rv8-6535, MINI-f4cx-fqj3-m8j3, UBUNTU-CVE-2026-11352

## What is CVE-2026-11352?

CVE-2026-11352 is a high-severity denial of service vulnerability in Haxx Curl, published on 3 Jul 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

An issue in curl’s QUIC UDP receive function allows a malicious HTTP/3 server
to trigger a remote denial of service against a curl or libcurl client.
Because the helper function discards zero-length UDP datagrams before counting
them toward the per-call packet budget, a connected QUIC peer can continuously
stream empty datagrams to indefinitely stall the client.

Weakness: CWE-835 (Loop with Unreachable Exit Condition)

## Which versions are affected by CVE-2026-11352?

It affects 1 product.


Products: Haxx Curl.

## How do I fix CVE-2026-11352?

Upgrade to a fixed version.

## Is CVE-2026-11352 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-11352 exists.

## Other vulnerabilities in Haxx Curl

- [CVE-2026-19931](https://insights.sbomify.com/CVE-2026-19931/): Negotiate ambient user conn reuse (critical 9.8)
- [CVE-2026-10536](https://insights.sbomify.com/CVE-2026-10536/): HTTP/2 stream-dependency tree UAF (critical 9.8)
- [CVE-2026-11856](https://insights.sbomify.com/CVE-2026-11856/): cross-origin Digest auth state leak (critical 9.8)
- [CVE-2026-8925](https://insights.sbomify.com/CVE-2026-8925/): SASL double-free (critical 9.8)
- [CVE-2026-9079](https://insights.sbomify.com/CVE-2026-9079/): stale proxy password leak (critical 9.8)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-11352 and fix it if it is affected.

What it is: CVE-2026-11352 is a high-severity denial of service vulnerability in Haxx Curl, published on 3 Jul 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Exploitation: It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-11352 exists.

Affected product: Haxx Curl. 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-2026-11352/ (Markdown: https://insights.sbomify.com/CVE-2026-11352/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-11352
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-11352
- OSV: https://osv.dev/vulnerability/CVE-2026-11352

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-11352/
Summaries are generated and may contain mistakes; the official description above is the record.