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High, CVSS 7.5

Improper Handling of Exceptional Conditions and Improper Input Validation in Reactor Netty

CVE-2020-5403GHSA-hp5x-rqf7-43vf

What to do

Vendor fix available. Upgrade each affected package to the fixed version on its release line (io.projectreactor.netty:reactor-netty-http 0.9.5), redeploy, then verify what is actually installed.

This page has no inventory attached, so it cannot say whether you are affected. A vendor fix is not proof that your deployment is fixed.

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Affected packages

Sources

Severity and exploitation
Exploitation
No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.
CVSS
7.5 · CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
EPSS
  • CVE-2020-5403: 1.16% estimated exploitation activity in the next 30 days; percentile 67.08 (FIRST EPSS, 2026-11-03). This is a model estimate, not proof of exploitation or customer exposure.
Source description

As published by the source; long descriptions are shortened.

Reactor Netty HttpServer, versions 0.9.3 and 0.9.4, is exposed to a URISyntaxException that causes the connection to be closed prematurely instead of producing a 400 response.

Dates and revisions
Published by the source
Last modified by the source
Source last checked
  1. Revision 1 · created ·

    Published from ghsa record GHSA-hp5x-rqf7-43vf

Agent brief

Preview the exact text before you copy it. Commands are read-only suggestions; review them before running anything.

# Patch Next advisory brief: CVE-2020-5403

Advisory: Improper Handling of Exceptional Conditions and Improper Input Validation in Reactor Netty
IDs: CVE-2020-5403, GHSA-hp5x-rqf7-43vf
Record: https://patchnext.com/advisories/cve-2020-5403 (revision 1, source checked 26 Oct 2026, 16:02 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: High (CVSS 7.5)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: io.projectreactor.netty:reactor-netty-http 0.9.5. A vendor fix does not mean a deployment is fixed.

## Affected components
- Maven io.projectreactor.netty:reactor-netty-http: affected >= 0.9.3, <= 0.9.4; fixed in 0.9.5

## Suggested inspection (read-only)
- Maven io.projectreactor.netty:reactor-netty-http: 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 io.projectreactor.netty:reactor-netty-http.
- 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-hp5x-rqf7-43vf (GitHub-reviewed advisory GHSA-hp5x-rqf7-43vf lists affected ranges: Maven io.projectreactor.netty:reactor-netty-http >=0.9.3 <=0.9.4)

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