---
id: "CVE-2026-91395"
kind: "vulnerability"
aliases: ["CVE-2026-91395"]
title: "Oracle Java SE and GraalVM: network attacker can alter data or cause partial denial of service"
severity: "medium"
cvss: 6.5
epss: 0.00253
exploited: false
status: "open"
category: "runtime"
products: []
ecosystems: []
tags: ["graalvm", "java", "oracle-jdk", "runtime", "self-hosted"]
not_affected_if: ["no-network-exposed-utility-api", "unaffected-jdk-build"]
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-2026-91395", "first_seen_at": "2026-10-23T21:57:26+00:00"}, {"source": "epss", "url": "https://api.first.org/data/v1/epss?cve=CVE-2026-91395", "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

Oracle Java SE and GraalVM for JDK ship a flaw in the Utility component that an unauthenticated network attacker can reach through APIs, for example via a web service that passes data to them. A successful attack can let the attacker modify or delete some accessible data and partly disrupt the Java process.

_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: Oracle 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 that accepts untrusted network input runs on one of those builds

## Fix

- Move Oracle Java SE, GraalVM for JDK or GraalVM Enterprise Edition to a release newer than the affected versions listed above, using the vendor's April 2026 Critical Patch Update build
- Unknown exact fixed build numbers: the sources do not name them

## Timeline

- 2026-10-23T21:57:26+00:00 nvd https://nvd.nist.gov/vuln/detail/CVE-2026-91395
- 2026-10-25T12:38:52+00:00 epss https://api.first.org/data/v1/epss?cve=CVE-2026-91395

## 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_