---
id: "CVE-2026-101584"
kind: "vulnerability"
aliases: ["CVE-2026-101584"]
title: "Helidon WebSocket client flaw lets unauthenticated attackers read data and cause partial denial of service"
severity: "medium"
cvss: 6.5
epss: null
exploited: false
status: "open"
category: "package"
products: []
ecosystems: []
tags: ["helidon", "java", "oracle-fusion-middleware", "package"]
not_affected_if: ["no-websocket-client", "other-helidon-version"]
published_at: "2026-10-20T22:18:11+00:00"
first_seen_at: "2026-10-23T21:57:22+00:00"
updated_at: "2026-10-25T03:55:13+00:00"
sources: [{"source": "nvd", "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-101584", "first_seen_at": "2026-10-23T21:57:22+00:00"}]
---

# Helidon WebSocket client flaw lets unauthenticated attackers read data and cause partial denial of service

The helidon-webclient-websocket component of Oracle's Helidon framework has a flaw reachable over HTTP without credentials. A remote attacker can read a subset of data Helidon can access and partially disrupt the service.

_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 the `io.helidon` dependency version in `pom.xml` or `build.gradle`) and see whether it falls in `4.0.0` through `4.5.5` or `27.0.0`.
- Confirm whether the application uses the `helidon-webclient-websocket` artifact.

## Fix

- Move Helidon past the affected range to a fixed release listed in Oracle's advisory (the sources do not name the exact fixed version).

## Timeline

- 2026-10-23T21:57:22+00:00 nvd https://nvd.nist.gov/vuln/detail/CVE-2026-101584

## From the sources

Vulnerability in the Helidon product of Oracle Fusion Middleware (component: helidon-webclient-websocket).  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 read access to a subset of Helidon accessible data and unauthorized ability to cause a partial denial of service (partial DOS) of Helidon. CVSS 3.1 Base Score 6.5 (Confidentiality and Availability impacts).  CVSS Vector: (CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:L).

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_Free to read at a human pace. An API with keys and an MCP server are in preparation; early access: hello@infrastack.ai_