---
id: "CVE-2026-83378"
kind: "vulnerability"
aliases: ["CVE-2026-83378"]
title: "Oracle Java SE: compiler flaw lets remote attackers change some data"
severity: "medium"
cvss: 4.8
epss: null
exploited: false
status: "open"
category: "runtime"
products: []
ecosystems: []
tags: ["java", "oracle-jdk", "runtime", "self-hosted", "web-services"]
not_affected_if: ["default-config"]
published_at: "2026-10-20T22:19:54+00:00"
first_seen_at: "2026-10-23T21:57:25+00:00"
updated_at: "2026-10-25T04:33:17+00:00"
sources: [{"source": "nvd", "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-83378", "first_seen_at": "2026-10-23T21:57:25+00:00"}]
---

# Oracle Java SE: compiler flaw lets remote attackers change some data

A flaw in the Java SE Compiler component lets an unauthenticated attacker over the network read and modify a subset of data that Java SE can reach, by supplying crafted data to APIs such as through a web service. Exploitation is difficult, and the sources rate it CVSS 4.8 medium with no confidentiality or integrity loss beyond a subset of 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 releases 21.0.12.1, 25.0.4.1 and 27.
- Check whether the application runs on an Oracle Java SE build listed as affected.

## Fix

- Move Oracle Java SE to a patched release from the April 2026 Critical Patch Update (exact fixed versions: unknown in the sources).

## Timeline

- 2026-10-23T21:57:25+00:00 nvd https://nvd.nist.gov/vuln/detail/CVE-2026-83378

## From the sources

Vulnerability in Oracle Java SE (component: Compiler).  Supported versions that are affected are Oracle Java SE: 21.0.12.1, 25.0.4.1 and  27. Difficult to exploit vulnerability allows unauthenticated attacker with network access via multiple protocols to compromise Oracle Java SE.  Successful attacks of this vulnerability can result in  unauthorized update, insert or delete access to some of Oracle Java SE accessible data as well as  unauthorized read access to a subset of Oracle Java SE 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 4.8 (Confidentiality and Integrity impacts).  CVSS Vector: (CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:N).

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