---
title: "CVE-2026-91484: Oracle Java SE - Broken Access Control"
description: "Oracle Java SE 8u503 and 8u503-perf contain a broken access control vulnerability caused by sandbox bypass in Java plugin, letting low privileged logged-in attackers modify or access critical data, exploit requires running untrusted code in sandboxed Java Web Start or applets."
url: https://panop.io/threat-heartbeat/CVE-2026-91484/
---

# CVE-2026-91484 Oracle Java SE - Broken Access Control

Oracle Java SE 8u503 and 8u503-perf contain a broken access control vulnerability caused by sandbox bypass in Java plugin, letting low privileged logged-in attackers modify or access critical data, exploit requires running untrusted code in sandboxed Java Web Start or applets.

CVSS base score 7.5 /10

High

CISA KEV

Not listed

Public exploit

None known

Authentication

Required

[View the NVD record ↗](https://nvd.nist.gov/vuln/detail/CVE-2026-91484)

## Details

Type

Broken Access Control

Impact

Data Tampering, Information Disclosure

CVSS vector

CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:C/C:H/I:H/A:N

Published

20 October 2026

Updated

21 October 2026

## Vendor fix

Update to the latest available version beyond 8u503.

Patching closes this CVE. It does not tell you which of your systems run the affected version, or what else is exposed alongside them.

## References

- [https://nvd.nist.gov/vuln/detail/CVE-2026-91484](https://nvd.nist.gov/vuln/detail/CVE-2026-91484)
- [https://www.oracle.com/security-alerts/cpuoct2026.html](https://www.oracle.com/security-alerts/cpuoct2026.html)

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## What this record can't tell you

- Whether you run the affected software, and where
- Whether an attacker can actually reach and exploit it
- The misconfigurations that never get a CVE number
- What it would cost the business, ranked into what to fix first

Panop answers these inside your environment, for this CVE and every other finding.

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