---
title: "CVE-2026-91403: Oracle Corporation Oracle Java SE vulnerability"
url: https://erroneo.us/security/cve/CVE-2026-91403/
description: "CVE-2026-91403 (Oracle Corporation Oracle Java SE): Vulnerability in the Oracle Java SE, Oracle GraalVM for JDK, Oracle GraalVM Enterprise Edition product…"
type: vulnerability-record
section: "Security Digest"
date_published: 2026-10-21
date_modified: 2026-10-21
publisher: erroneo.us
author: erroneo.us Security Desk
cve: "CVE-2026-91403"
kev: false
cvss: 9.1
epss: null
license: All rights reserved. Quote with attribution and a link.
---

# CVE-2026-91403: Oracle Corporation Oracle Java SE vulnerability

**Signal:** Critical and remotely reachable. No known exploitation yet, but it is network-reachable without credentials. (Computed from CISA KEV, EPSS and CVSS; not an editorial verdict.)

## Should you act?

- No confirmed exploitation. It is not in CISA’s KEV catalog. That can change quickly after a public write-up; re-check if you are affected.
- Remotely reachable with no login and no user interaction. If the vulnerable service is exposed to the internet, prioritize it.
- Editorial verdict: Patch this week. eMudhra CA Key Compromise: Update Non-Browser TLS Clients — Anyone can mint certificates from these broken CA keys, but only clients that skip Certificate Transparency and still trust the emSign root are exposed, and only to an on-path attacker: update those trust bundles this week, build machines first.

## What it is

Vulnerability in the Oracle Java SE, Oracle GraalVM for JDK, Oracle GraalVM Enterprise Edition product of Oracle Java SE (component: JSSE). Supported versions that are affected are Oracle Java SE: 8u511, 8u511-perf, 11.0.33, 17.0.21, 21.0.13, 25.0.5, 27.0.1; Oracle GraalVM for JDK: 17.0.21 and 21.0.13; Oracle GraalVM Enterprise Edition: 21.3.20. 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 creation, deletion or modification access to critical data or all Oracle Java SE, Oracle GraalVM for JDK, Oracle GraalVM Enterprise Edition accessible data as well as unauthorized access to critical data or complete access to all 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 9.1 (Confidentiality and Integrity impacts). CVSS Vector: (CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N).

## Affected products (CVE record)

- Oracle Corporation Oracle Java SE: 8u511, 8u511-perf, 11.0.33, 17.0.21, 21.0.13, 25.0.5, 27.0.1
- Oracle Corporation Oracle GraalVM for JDK: 17.0.21, 21.0.13
- Oracle Corporation Oracle GraalVM Enterprise Edition: 21.3.20

## Severity

- oracle CVSS 3.1: 9.1 `CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N`

## Exploitation

- CISA KEV: not listed (no confirmed in-the-wild exploitation known to CISA).

## Sources

- [Oracle Advisory](https://www.oracle.com/security-alerts/alert-cve-2026-91403.html)
- [CVE.org record CVE-2026-91403](https://www.cve.org/CVERecord?id=CVE-2026-91403)
- [NVD entry CVE-2026-91403](https://nvd.nist.gov/vuln/detail/CVE-2026-91403)

---
Source page: https://erroneo.us/security/cve/CVE-2026-91403/ · Security Digest: https://erroneo.us/security/ · More: https://erroneo.us/llms.txt