---
id: "CVE-2026-101587"
kind: "vulnerability"
aliases: ["CVE-2026-101587"]
title: "Helidon HTTP/1 web client: unauthenticated request can cause partial denial of service"
severity: "medium"
cvss: 5.3
epss: null
exploited: false
status: "open"
category: "package"
products: []
ecosystems: []
tags: ["helidon", "java", "oracle-fusion-middleware", "package"]
not_affected_if: ["unaffected-version"]
published_at: "2026-10-20T22:18:12+00:00"
first_seen_at: "2026-10-23T21:57:22+00:00"
updated_at: "2026-10-25T04:23:16+00:00"
sources: [{"source": "nvd", "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-101587", "first_seen_at": "2026-10-23T21:57:22+00:00"}]
---

# Helidon HTTP/1 web client: unauthenticated request can cause partial denial of service

Helidon's HTTP/1 web client component (helidon-webclient-http1) affects versions 4.0.0 through 4.5.5 and 27.0.0, according to the sources. An unauthenticated attacker with network access over HTTP can cause a partial denial of service, with no confidentiality or integrity impact.

_Summary, check and fix written by a model from the sources; labelled as such._

## How to check

- Check the Helidon version in the project's build file (for example `pom.xml` or `build.gradle`) and look for `helidon-webclient-http1` in the dependency tree
- Run `mvn dependency:tree | grep helidon-webclient-http1` or the Gradle equivalent to confirm the resolved version

## Fix

- Move `helidon-webclient-http1` and related Helidon artifacts to a version outside the affected ranges 4.0.0-4.5.5 and 27.0.0; the sources do not name the fixed version
- Check the Oracle advisory for the patched release number

## Timeline

- 2026-10-23T21:57:22+00:00 nvd https://nvd.nist.gov/vuln/detail/CVE-2026-101587

## From the sources

Vulnerability in the Helidon product of Oracle Fusion Middleware (component: helidon-webclient-http1).  Supported versions that are affected are 4.0.0-4.5.5 and 27.0.0. Easily exploitable vulnerability allows unauthenticated attacker with network access via HTTP to compromise Helidon.  Successful attacks of this vulnerability can result in unauthorized ability to cause a partial denial of service (partial DOS) of Helidon. CVSS 3.1 Base Score 5.3 (Availability impacts).  CVSS Vector: (CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L).

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