---
id: "CVE-2026-91396"
kind: "vulnerability"
aliases: ["CVE-2026-91396"]
title: "Oracle Java SE and GraalVM: network attacker can alter data or cause partial denial of service"
severity: "medium"
cvss: 6.5
epss: 0.00332
exploited: false
status: "open"
category: "runtime"
products: []
ecosystems: []
tags: ["graalvm", "java", "jdk", "runtime", "self-hosted", "web-services"]
not_affected_if: ["no-untrusted-network-input", "patched-version"]
published_at: "2026-10-20T22:20:42+00:00"
first_seen_at: "2026-10-23T21:57:26+00:00"
updated_at: "2026-10-25T12:38:52+00:00"
sources: [{"source": "nvd", "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-91396", "first_seen_at": "2026-10-23T21:57:26+00:00"}, {"source": "epss", "url": "https://api.first.org/data/v1/epss?cve=CVE-2026-91396", "first_seen_at": "2026-10-25T12:38:52+00:00"}]
---

# Oracle Java SE and GraalVM: network attacker can alter data or cause partial denial of service

An unauthenticated attacker with network access can exploit a flaw in the Utility component of Oracle Java SE and GraalVM through APIs reached by a web service. Successful attacks can allow unauthorized update, insert or delete of some accessible data and a partial denial of service.

_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 releases: 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 any service feeds untrusted network data into Java APIs in the Utility component, such as a web service
- Check for sandboxed Java Web Start or applet use, which the advisory also covers

## Fix

- Upgrade Oracle Java SE to a release newer than 8u503, 8u503-perf or 11.0.32.1 (vendor patch level unknown from sources)
- Upgrade Oracle GraalVM for JDK to a release newer than 17.0.20.1 or 21.0.12.1
- Upgrade Oracle GraalVM Enterprise Edition to a release newer than 21.3.19.1.1
- Apply the vendor's Oracle Critical Patch Update for the affected product line

## Timeline

- 2026-10-23T21:57:26+00:00 nvd https://nvd.nist.gov/vuln/detail/CVE-2026-91396
- 2026-10-25T12:38:52+00:00 epss https://api.first.org/data/v1/epss?cve=CVE-2026-91396

## From the sources

Vulnerability in the Oracle Java SE, Oracle GraalVM for JDK, Oracle GraalVM Enterprise Edition product of Oracle Java SE (component: Utility).  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. Easily exploitable 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 update, insert or delete access to some of Oracle Java SE, Oracle GraalVM for JDK, Oracle GraalVM Enterprise Edition accessible data and unauthorized ability to cause a partial denial of service (partial DOS) of Oracle Java SE, Oracle GraalVM for JDK, Oracle GraalVM Enterprise Edition. 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:L/PR:N/UI:N/S:U/C:N/I:L/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_