---
id: "CVE-2026-91453"
kind: "vulnerability"
aliases: ["CVE-2026-91453"]
title: "Oracle Java SE: Lightweight HTTP Server flaw allows unauthorized data changes"
severity: "medium"
cvss: 5.3
epss: 0.00282
exploited: false
status: "open"
category: "runtime"
products: []
ecosystems: []
tags: ["graalvm", "java", "oracle-jdk", "runtime", "self-hosted"]
not_affected_if: ["component-unused", "patched-java-version"]
published_at: "2026-10-20T22:20:49+00:00"
first_seen_at: "2026-10-23T21:57:27+00:00"
updated_at: "2026-10-25T12:38:52+00:00"
sources: [{"source": "nvd", "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-91453", "first_seen_at": "2026-10-23T21:57:27+00:00"}, {"source": "epss", "url": "https://api.first.org/data/v1/epss?cve=CVE-2026-91453", "first_seen_at": "2026-10-25T12:38:52+00:00"}]
---

# Oracle Java SE: Lightweight HTTP Server flaw allows unauthorized data changes

A flaw in the Lightweight HTTP Server component of Oracle Java SE and GraalVM lets an unauthenticated network attacker make unauthorized updates, inserts or deletes to some accessible data. The attack works by supplying data to the component's APIs, such as through a web service, and needs no user action.

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

## How to check

- Run `java -version` and compare the output with the affected Java SE releases listed in the advisory.
- Check whether your application uses the Lightweight HTTP Server API (`com.sun.net.httpserver`).

## Fix

- Oracle Java SE: move to a patched release from the Oracle Critical Patch Update (for example `8u503`, `11.0.32.1`, `17.0.20.1`, `21.0.12.1` or `25.0.4.1`, depending on your line).
- Oracle GraalVM for JDK: move to `17.0.20.1` or `21.0.12.1`.
- Oracle GraalVM Enterprise Edition: move to a release newer than `21.3.19.1.1`.

## Timeline

- 2026-10-23T21:57:27+00:00 nvd https://nvd.nist.gov/vuln/detail/CVE-2026-91453
- 2026-10-25T12:38:52+00:00 epss https://api.first.org/data/v1/epss?cve=CVE-2026-91453

## From the sources

Vulnerability in the Oracle Java SE, Oracle GraalVM for JDK, Oracle GraalVM Enterprise Edition product of Oracle Java SE (component: Lightweight HTTP Server).  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. 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. Note: This vulnerability can only be exploited by supplying data to APIs in the specified Component without using Untrusted Java Web Start applications or Untrusted Java applets, such as through a web service. CVSS 3.1 Base Score 5.3 (Integrity impacts).  CVSS Vector: (CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N).

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