DOS vulnerability for Quoted Quality CSV headers

Exploitation

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

CVSS

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

EPSS

• CVE-2020-27223: 78.03% estimated exploitation activity in the next 30 days; percentile 99.58 (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.

Impact When Jetty handles a request containing request headers with a large number of “quality” (i.e. q) parameters (such as what are seen on the Accept, Accept-Encoding, and Accept-Language request headers), the server may enter a denial of service (DoS) state due to high CPU usage while sorting the list of values based on their quality values. A single request can easily consume minutes of CPU time before it is even dispatched to the application. The only features within Jetty that can trigger this behavior are: - Default Error Handling - the Accept request header with the QuotedQualityCSV is used to determine what kind of content to send back to the client (html, text, json, xml, etc) - StatisticsServlet - uses the Accept request header with the QuotedQualityCSV to determine what kind of content to send back to the client (xml, json, text, html, etc) - HttpServletRequest.getLocale() - uses the Accept-Language request header with the QuotedQualityCSV to determine which “preferred”…

Published by the source

10 Mar 2021, 03:46 UTC

Last modified by the source

1 Feb 2023, 05:05 UTC

Source last checked

26 Oct 2026, 16:06 UTC

1. Revision 1 · created · 26 Oct 2026

   Published from ghsa record GHSA-m394-8rww-3jr7

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# Patch Next advisory brief: CVE-2020-27223

Advisory: DOS vulnerability for Quoted Quality CSV headers
IDs: CVE-2020-27223, GHSA-m394-8rww-3jr7
Record: https://patchnext.com/advisories/cve-2020-27223 (revision 1, source checked 26 Oct 2026, 16:06 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: Medium (CVSS 5.3)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: org.eclipse.jetty:jetty-server 11.0.1, 10.0.1, 9.4.37. A vendor fix does not mean a deployment is fixed.

## Affected components
- Maven org.eclipse.jetty:jetty-server: affected >= 9.4.6, < 9.4.37; >= 10.0.0, <= 10.0.0; >= 11.0.0, <= 11.0.0; fixed in 11.0.1, 10.0.1, 9.4.37

## Suggested inspection (read-only)
- Maven org.eclipse.jetty:jetty-server: 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 org.eclipse.jetty:jetty-server.
- 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-m394-8rww-3jr7 (GitHub-reviewed advisory GHSA-m394-8rww-3jr7 lists affected ranges: Maven org.eclipse.jetty:jetty-server >=9.4.6 =10.0.0 =11.0.0 <=11.0.0)

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