HTTP Response Splitting in Styx

Exploitation

No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.

CVSS

6.5 · CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:H/A:N

EPSS

• CVE-2020-6858: 1.16% estimated exploitation activity in the next 30 days; percentile 67.25 (FIRST EPSS, 2026-11-03). This is a model estimate, not proof of exploitation or customer exposure.

As published by the source; long descriptions are shortened.

Vulnerability Styx is vulnerable to CWE-113: Improper Neutralization of CRLF Sequences in HTTP Headers ('HTTP Response Splitting'). Vulnerable Component The vulnerable component is the com.hotels.styx.api.HttpHeaders.Builder due to disabling the HTTP Header validation built into Netty in these locations: https://github.com/HotelsDotCom/styx/blob/e1d578e9b9c38df9cd19c21dc2eb9b949d85b558/components/api/src/main/java/com/hotels/styx/api/HttpHeaders.java#L145 https://github.com/HotelsDotCom/styx/blob/e1d578e9b9c38df9cd19c21dc2eb9b949d85b558/components/api/src/main/java/com/hotels/styx/api/HttpHeaders.java#L145 new DefaultHttpHeaders(false) disables the built-in validation in Netty. Either use the default constructor or new DefaultHttpHeaders(true instead. Additionally, another vulnerable component is the StyxToNettyResponseTranslator due to also disabling the HTTP Header validation built into netty in this location.…

Published by the source

3 Mar 2020, 15:32 UTC

Last modified by the source

9 Jan 2023, 05:02 UTC

Source last checked

26 Oct 2026, 15:52 UTC

1. Revision 1 · created · 26 Oct 2026

   Published from ghsa record GHSA-6v7p-v754-j89v

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# Patch Next advisory brief: CVE-2020-6858

Advisory: HTTP Response Splitting in Styx
IDs: CVE-2020-6858, GHSA-6v7p-v754-j89v
Record: https://patchnext.com/advisories/cve-2020-6858 (revision 1, source checked 26 Oct 2026, 15:52 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: Medium (CVSS 6.5)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: com.hotels.styx:styx-api 1.0.0-rc1. A vendor fix does not mean a deployment is fixed.

## Affected components
- Maven com.hotels.styx:styx-api: affected <= 1.0.0.beta8; fixed in 1.0.0-rc1

## Suggested inspection (read-only)
- Maven com.hotels.styx:styx-api: check the installed version with your package manager.

## Supported action
Upgrade each affected component to a fixed version on its release line. For a transitive dependency, upgrade the parent package or add an override or constraint, then regenerate the lockfile. Redeploy every environment that ran an affected version.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on com.hotels.styx:styx-api.
- Repeat the inspection and confirm that only fixed versions remain installed.

## Rollback considerations
- Keep the previous lockfile and deployment artifact. Rolling back reinstates the vulnerable version, so apply any documented mitigation while you fix forward.

## Unresolved questions
- Which deployments run an affected version?
- Exploitation status can change. Check again before lowering the priority.
- Mark the work resolved only after the fixed version is verified in production.

## Sources
- Verified: https://github.com/advisories/GHSA-6v7p-v754-j89v (GitHub-reviewed advisory GHSA-6v7p-v754-j89v lists affected ranges: Maven com.hotels.styx:styx-api >=0 <=1.0.0.beta8)

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