Cloudanix VulnDB

CVE-2026-91396

Medium · 6.5

CVSS

6.5

EPSS

0.3%

Published

Oct 20, 2026

CISA due date

—

Cloudanix analysis

Next patch cycle SSVC: Track

A flaw in certain Oracle Java products lets remote attackers change some data and partially disrupt services without needing any login credentials.

Exploitation
Remote Unauthenticated
Attacker needs
None
Complexity
Low
Impact
Data Tampering
Component
Library
Class
Improper Input Validation
Remediation
Upgrade
Effort
Medium
Patch risk
Low

What it actually does

Improper input validation in the Utility component permits unauthenticated network attackers to perform unauthorized data modifications (insert/update/delete) and induce partial denial of service via crafted inputs supplied to exposed APIs.

Why it matters to the business

Attackers can alter limited application data and degrade service availability in Java SE and GraalVM deployments without authentication, potentially affecting client-side sandboxed applications that process untrusted code from the internet.

How an attack unfolds

An unauthenticated attacker with network access crafts malicious inputs and sends them through multiple protocols to the Utility component APIs; successful validation bypass results in partial data tampering and availability impact. The same vector applies to sandboxed Java Web Start or applet deployments that load untrusted internet-sourced code.

How to fix it

Apply the latest Oracle Critical Patch Update that addresses this issue in the Utility component for the affected Java SE, GraalVM for JDK, and GraalVM Enterprise Edition releases. Where immediate patching is not feasible, restrict network exposure of the affected APIs and enforce strict input validation at application boundaries.

How to confirm the fix worked

Confirm deployment of patched Java versions listed in the Oracle advisory, re-test API endpoints with previously successful malicious payloads to verify rejection, and review sandbox policy configurations for untrusted code execution paths.

Typical attack path

  1. Locate publicly reachable Oracle Java SE, GraalVM for JDK, or GraalVM Enterprise Edition instances exposing Utility component APIs
  2. Submit specially crafted data via network protocols to trigger improper input handling
  3. Achieve unauthorized modification of accessible data and partial denial of service

How to detect it

Inspect application and API access logs for unexpected or malformed inputs targeting Utility component entry points; correlate with partial service degradation events and review Java sandbox policy violations in client deployments processing external code.

What your security team should do

  • Prioritize patching of internet-facing or high-value Java SE and GraalVM instances within the next maintenance window
  • Review and restrict network accessibility of Utility component APIs to trusted sources only
  • Monitor Oracle release notes for exact fixed versions and schedule upgrades accordingly
  • Audit sandboxed Java application deployments that accept untrusted code

The record

Vulnerability in the Oracle Java SE, Oracle GraalVM for JDK, Oracle GraalVM Enterprise Edition product of Oracle Java SE (component: Utility). 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. 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 and unauthorized ability to cause a partial denial of service (partial DOS) of Oracle Java SE, Oracle GraalVM for JDK, Oracle GraalVM Enterprise Edition. 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:L/PR:N/UI:N/S:U/C:N/I:L/A:L).

Affected packages

Ecosystem Package Introduced Fixed

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