# CVE-2026-19203: A client may issue specially crafted HTTP/1.1 chunked requests to a Jetty server that cause Jetty and an intermediary proxy to interpret dif


- **Severity:** High 8.3 (`CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:L/VI:H/VA:N/SC:N/SI:N/SA:N`)
- **Exploited in the wild:** Not known
- **Fix available:** Yes
- **Published:** 8 Sep 2026
- **Updated:** 8 Sep 2026
- **Also known as:** CLEANSTART-2026-HU83595, CLEANSTART-2026-IE92648, CLEANSTART-2026-IM74303, CLEANSTART-2026-LJ21739, CLEANSTART-2026-MJ80474, CLEANSTART-2026-NQ39719, CLEANSTART-2026-RD18751, CLEANSTART-2026-ZJ59576, DEBIAN-CVE-2026-19203, GHSA-p2j5-5566-vpv9, GHSA-xc35-c22g-239h, UBUNTU-CVE-2026-19203

## What is CVE-2026-19203?

CVE-2026-19203 is a high-severity vulnerability in Eclipse Jetty, published on 8 Sep 2026. 

### Official description

A client may issue specially crafted HTTP/1.1 chunked requests to a Jetty server that cause Jetty and an intermediary proxy to interpret different request boundaries, potentially resulting in HTTP request smuggling.

This is caused by Jetty accepting a lone LF character as a terminator in parts of chunked request parsing. Depending on the Jetty version and configured HTTP compliance mode, this may occur in chunk extensions, chunk data termination, or trailer termination.

Weakness: CWE-444 (Inconsistent Interpretation of HTTP Requests)

## Which versions are affected by CVE-2026-19203?


## How do I fix CVE-2026-19203?

Upgrade to a fixed version.

## Is CVE-2026-19203 being exploited?

There is no known exploitation of CVE-2026-19203 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-19203 and fix it if it is affected.

What it is: CVE-2026-19203 is a high-severity vulnerability in Eclipse Jetty, published on 8 Sep 2026. 
Exploitation: There is no known exploitation of CVE-2026-19203 in the wild and no public exploit code.

Affected product: Eclipse Jetty. 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-2026-19203/ (Markdown: https://insights.sbomify.com/CVE-2026-19203/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-19203
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-19203
- OSV: https://osv.dev/vulnerability/CVE-2026-19203

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-19203/
Summaries are generated and may contain mistakes; the official description above is the record.