CVE-2026-47013: Oracle Java SE JavaFX DoS Vulnerability

CVE-2026-47013 Overview

CVE-2026-47013 is a network-exploitable vulnerability in the JavaFX component of Oracle Java SE version 8u491. An unauthenticated attacker with network access can trigger the flaw through multiple protocols to cause a partial denial of service (DoS). The weakness is classified under [CWE-770] (Allocation of Resources Without Limits or Throttling), indicating uncontrolled resource consumption.

Exploitation requires no user interaction and no privileges. The flaw affects Java deployments that load untrusted code, including sandboxed Java Web Start applications and applets receiving data through exposed APIs or web services.

Critical Impact
Unauthenticated remote attackers can cause a partial availability loss in Oracle Java SE 8u491 through JavaFX APIs reachable over the network.

Affected Products

Oracle Java SE 8u491 (JavaFX component)
Java Web Start sandboxed applications on the affected version
Sandboxed Java applets running on the affected version

Discovery Timeline

2026-07-21 - CVE-2026-47013 published to NVD
2026-07-23 - Last updated in NVD database
July 2026 - Addressed in the Oracle Critical Patch Update Advisory - July 2026

Technical Details for CVE-2026-47013

Vulnerability Analysis

The vulnerability resides in the JavaFX component shipped with Oracle Java SE 8u491. JavaFX exposes APIs that process data supplied by callers, including remote web services. When these APIs receive crafted inputs, the underlying implementation fails to constrain resource allocation, producing a partial availability impact on the affected Java process.

The flaw is remotely reachable, requires low attack complexity, and needs no authentication or user interaction. Exploitation does not lead to code execution or data disclosure. The scope is limited to degraded service availability of the Java runtime hosting the vulnerable JavaFX code.

Root Cause

The root cause aligns with [CWE-770]: resources allocated during JavaFX API processing are not properly bounded or throttled. An attacker who feeds malicious data through a web service or protocol endpoint can force the runtime to consume resources beyond expected limits, degrading the application's responsiveness.

Attack Vector

The attack vector is the network. Two primary exposure patterns exist:

Server-side or client-side applications that pass externally supplied data into JavaFX APIs, for example through a web service front-end.
Sandboxed Java Web Start applications or applets that load untrusted code from the internet and depend on the Java sandbox for isolation.

Exploitation code details have not been published. See the Oracle Security Alert July 2026 for vendor guidance.

Detection Methods for CVE-2026-47013

Indicators of Compromise

Unexplained spikes in CPU, memory, or thread count within Java processes running JavaFX workloads.
Repeated inbound requests to web services or endpoints that forward data into JavaFX APIs from untrusted sources.
Java Web Start or applet sessions terminating abnormally or hanging after processing remote content.

Detection Strategies

Inventory hosts running Oracle Java SE 8u491 and identify applications that use JavaFX components.
Correlate network traffic to Java-hosted services with process-level resource metrics to surface DoS patterns.
Review application logs for JavaFX API exceptions, timeouts, or resource allocation failures.

Monitoring Recommendations

Enable JVM-level telemetry (garbage collection, thread pool, and heap metrics) on hosts running JavaFX applications.
Alert on sustained availability degradation of services dependent on Java SE 8u491.
Monitor egress from client endpoints running sandboxed Java content to identify unexpected loads of untrusted code.

How to Mitigate CVE-2026-47013

Immediate Actions Required

Apply the July 2026 Oracle Critical Patch Update to any system running Oracle Java SE 8u491.
Restrict network exposure of services that forward untrusted data into JavaFX APIs until patching is complete.
Disable Java Web Start and browser-based applet execution on endpoints that do not require them.

Patch Information

Oracle addressed this vulnerability in the July 2026 Critical Patch Update. Refer to the Oracle Security Alert July 2026 for the specific fixed versions and installation guidance.

Workarounds

Remove or upgrade Oracle Java SE 8u491 where JavaFX is not required.
Place rate limiting and input validation in front of web services that pass data to JavaFX APIs.
Enforce allowlists for code-signing certificates used by Java Web Start and applet deployments to prevent untrusted code from reaching the sandbox.

bash

# Verify installed Java SE version to confirm exposure
java -version

# On Windows, list Java installations via WMIC
wmic product where "Name like 'Java%%'" get Name, Version