---
id: "CVE-2026-91411"
kind: "vulnerability"
aliases: ["CVE-2026-91411"]
title: "Oracle Java SE: JGSS flaw lets unauthenticated network attacker crash or alter data"
severity: "medium"
cvss: 6.5
epss: null
exploited: false
status: "open"
category: "runtime"
products: []
ecosystems: []
tags: ["graalvm", "java", "oracle-jdk", "runtime", "self-hosted"]
not_affected_if: ["default-config"]
published_at: "2026-10-20T22:20:44+00:00"
first_seen_at: "2026-10-23T21:57:26+00:00"
updated_at: "2026-10-25T03:50:48+00:00"
sources: [{"source": "nvd", "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-91411", "first_seen_at": "2026-10-23T21:57:26+00:00"}]
---

# Oracle Java SE: JGSS flaw lets unauthenticated network attacker crash or alter data

A flaw in the JGSS component of Oracle Java SE, Oracle GraalVM for JDK and GraalVM Enterprise Edition can be triggered over the network without credentials. A successful attack can hang or repeatedly crash the Java process and gives limited unauthorized update, insert or delete access to some data.

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

## How to check

- Run `java -version` and compare against the affected versions: Java SE 8u503, 8u503-perf, 11.0.32.1; GraalVM for JDK 17.0.20.1 and 21.0.12.1; GraalVM Enterprise Edition 21.3.19.1.1.
- Check whether GraalVM for JDK or GraalVM Enterprise Edition is the runtime in use, not only a system Java.

## Fix

- Move Oracle Java SE to the Oracle patched release for the affected line (the sources do not name a fixed version).
- Move GraalVM for JDK and GraalVM Enterprise Edition to their patched releases (versions unknown from the sources).

## Timeline

- 2026-10-23T21:57:26+00:00 nvd https://nvd.nist.gov/vuln/detail/CVE-2026-91411

## From the sources

Vulnerability in the Oracle Java SE, Oracle GraalVM for JDK, Oracle GraalVM Enterprise Edition product of Oracle Java SE (component: JGSS).  Supported versions that are affected are Oracle Java SE: 8u503, 8u503-perf, 11.0.32.1;    Oracle GraalVM for JDK: 17.0.20.1 and  21.0.12.1;   Oracle GraalVM Enterprise Edition: 21.3.19.1.1. Difficult to exploit vulnerability allows unauthenticated attacker with network access via multiple protocols to compromise Oracle Java SE, Oracle GraalVM for JDK, Oracle GraalVM Enterprise Edition.  Successful attacks of this vulnerability can result in unauthorized ability to cause a hang or frequently repeatable crash (complete DOS) of Oracle Java SE, Oracle GraalVM for JDK, Oracle GraalVM Enterprise Edition as well as  unauthorized update, insert or delete access to some of Oracle Java SE, Oracle GraalVM for JDK, Oracle GraalVM Enterprise Edition accessible data. Note: This vulnerability can be exploited by using APIs in the specified Component, e.g., through a web service which supplies data to the APIs. This vulnerability also applies to Java deployments, typically in clients running sandboxed Java Web Start applications or sandboxed Java applets, that load and run untrusted code (e.g., code that comes from the internet) and rely on the Java sandbox for security. CVSS 3.1 Base Score 6.5 (Integrity and Availability impacts).  CVSS Vector: (CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:H).

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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_