---
id: "CVE-2026-101588"
kind: "vulnerability"
aliases: ["CVE-2026-101588"]
title: "Helidon WebSocket flaw lets unauthenticated network attackers read some data"
severity: "medium"
cvss: 5.3
epss: null
exploited: false
status: "open"
category: "runtime"
products: []
ecosystems: []
tags: ["helidon", "java", "runtime", "self-hosted", "websocket"]
not_affected_if: ["no-helidon", "no-websocket-endpoints"]
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-2026-101588", "first_seen_at": "2026-10-23T21:57:22+00:00"}]
---

# Helidon WebSocket flaw lets unauthenticated network attackers read some data

Helidon, Oracle's Java microservices framework, has a flaw in its WebSocket component that an unauthenticated attacker can reach over HTTP. A successful attack gives read access to a subset of data that Helidon can reach.

_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 pom.xml or build file for `4.0.0` through `4.5.5` or `27.0.0`
- Confirm whether the application exposes WebSocket endpoints (unknown which endpoints are affected)

## Fix

- Move Helidon to a release newer than the affected range `4.0.0`-`4.5.5` and `27.0.0` (the fixed version is unknown from the sources)
- Check Oracle's Critical Patch Update advisory for the patched release (unknown)

## Timeline

- 2026-10-23T21:57:22+00:00 nvd https://nvd.nist.gov/vuln/detail/CVE-2026-101588

## From the sources

Vulnerability in the Helidon product of Oracle Fusion Middleware (component: 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. CVSS 3.1 Base Score 5.3 (Confidentiality impacts).  CVSS Vector: (CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N).

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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_