Cloudanix VulnDB

CVE-2026-91411

Medium · 6.5

CVSS

6.5

EPSS

0.3%

Published

Oct 20, 2026

CISA due date

—

Cloudanix analysis

Schedule a fix SSVC: Track

A problem in certain Oracle Java versions could let a remote attacker crash important systems or make small unauthorized changes to data without needing login credentials.

Exploitation
Remote Unauthenticated
Attacker needs
None
Complexity
High
Impact
Denial Of Service
Component
Library
Class
Denial of service
Remediation
Upgrade
Effort
Medium
Patch risk
Low

What it actually does

Flaw in the JGSS component permits unauthenticated remote attackers to trigger a hang or repeatable crash (complete DoS) and limited unauthorized data modification (update/insert/delete) via crafted network traffic over multiple protocols; exploitation is possible through exposed APIs or untrusted code loaded in sandboxed Java deployments.

Why it matters to the business

Service outages and partial data integrity loss in Java-dependent applications, with low immediate urgency due to difficult exploitation conditions and minimal observed threat activity five days after publication.

How an attack unfolds

An attacker with network access identifies a vulnerable Oracle Java SE or GraalVM instance exposing JGSS APIs, crafts and sends specially formed protocol messages that abuse the component to induce a crash or limited data changes; success requires precise conditions and can occur through web services or sandboxed applets processing untrusted input.

How to fix it

Upgrade Oracle Java SE beyond 8u503/8u503-perf/11.0.32.1, Oracle GraalVM for JDK beyond 17.0.20.1/21.0.12.1, and Oracle GraalVM Enterprise Edition beyond 21.3.19.1.1.1 to the latest vendor-provided security releases; restrict network exposure of JGSS APIs where possible.

How to confirm the fix worked

Confirm running Java versions exceed the listed vulnerable releases, review patch release notes for JGSS fixes, and perform functional testing of availability and data integrity under simulated load.

Typical attack path

  1. Scan for exposed Oracle Java SE or GraalVM instances with network-accessible JGSS APIs
  2. Craft malicious input targeting the JGSS component via supported protocols
  3. Deliver the payload through a web service or untrusted code path
  4. Trigger repeated crashes or limited unauthorized data operations

How to detect it

Review application and system logs for repeated Java process crashes or hangs originating from JGSS calls, correlate with inbound network traffic on multiple protocols, and inspect sandboxed applet or web service activity for unexpected data modification attempts.

What your security team should do

  • Prioritize inventory of all Oracle Java SE and GraalVM deployments within the next 30 days
  • Apply available patches immediately upon release given the DoS impact
  • Limit network accessibility of affected components and monitor for anomalous Java process terminations

The record

Vulnerability in the Oracle Java SE, Oracle GraalVM for JDK, Oracle GraalVM Enterprise Edition product of Oracle Java SE (component: JGSS). 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. Difficult to exploit 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 ability to cause a hang or frequently repeatable crash (complete DOS) of Oracle Java SE, Oracle GraalVM for JDK, Oracle GraalVM Enterprise Edition as well as 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 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:H/PR:N/UI:N/S:U/C:N/I:L/A:H).

Affected packages

Ecosystem Package Introduced Fixed

Related vulnerabilities