---
id: "CVE-2026-91380"
kind: "vulnerability"
aliases: ["CVE-2026-91380"]
title: "Oracle Java SE: Utility component flaw lets an attacker change some data"
severity: "medium"
cvss: 4.0
epss: 0.00096
exploited: false
status: "open"
category: "runtime"
products: []
ecosystems: []
tags: ["graalvm", "java", "oracle-java-se", "runtime", "self-hosted"]
not_affected_if: ["no-java-runtime", "patched-release"]
published_at: "2026-10-20T22:20:41+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-2026-91380", "first_seen_at": "2026-10-23T21:57:26+00:00"}, {"source": "epss", "url": "https://api.first.org/data/v1/epss?cve=CVE-2026-91380", "first_seen_at": "2026-10-25T12:38:52+00:00"}]
---

# Oracle Java SE: Utility component flaw lets an attacker change some data

A flaw in the Utility component of Oracle Java SE and GraalVM lets an unauthenticated attacker with access to the host read and modify some data handled by the runtime. The attack path is through APIs in that component, such as a web service that passes data into them, and sandboxed Java applets or Web Start apps running untrusted code.

_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: 8u503, 11.0.32.1, 17.0.20.1, 21.0.12.1, 25.0.4.1, 27.
- For GraalVM, check `native-image --version` against 17.0.20.1, 21.0.12.1 and 21.3.19.1.1.
- Check whether any sandboxed Java applets or Java Web Start apps run untrusted code on your clients.

## Fix

- Upgrade Oracle Java SE to the Oracle Critical Patch Update release that contains the fix for CVE-2026-91380 (exact fixed version: unknown).
- Upgrade Oracle GraalVM for JDK and GraalVM Enterprise Edition to a patched release (exact fixed versions: unknown).

## Timeline

- 2026-10-23T21:57:26+00:00 nvd https://nvd.nist.gov/vuln/detail/CVE-2026-91380
- 2026-10-25T12:38:52+00:00 epss https://api.first.org/data/v1/epss?cve=CVE-2026-91380

## 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, 17.0.20.1, 21.0.12.1, 25.0.4.1, 27; 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 logon to the infrastructure where Oracle Java SE, Oracle GraalVM for JDK, Oracle GraalVM Enterprise Edition executes 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 as well as  unauthorized read access to a subset 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 4.0 (Confidentiality and Integrity impacts).  CVSS Vector: (CVSS:3.1/AV:L/AC:H/PR:N/UI:N/S:U/C:L/I:L/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_