Is CVE-2026-21933 exploited in the wild?

No. Junglewise Threat Intelligence has no report of CVE-2026-21933 being exploited in the wild.

How severe is CVE-2026-21933?

Medium severity, with a CVSS score of 6.1, published 20 January 2026.

Which products and versions are affected?

Oracle GraalVM Enterprise Edition 21.3.16; Oracle Graalvm For Jdk 17.0.17, 21.0.9; Oracle Java SE 8u471, 8u471-b50, 8u471-perf, 11.0.29, 17.0.17, 21.0.9, 25.0.1; Siemens SIMATIC CN 4100 All versions < V5.0.

Is there a fix for CVE-2026-21933?

No fixed version is recorded yet. Check the vendor's advisory in the references below. If you run it, Junglewise drafts a mitigation that fits your setup and applies it once you approve, with senior security engineers behind it.

How is CVE-2026-21933 attacked?

It is attacked over the network, in a software library.

Am I affected by CVE-2026-21933?

Check whether you run Oracle GraalVM Enterprise Edition, Oracle Graalvm For Jdk, Oracle Java SE or one of the others listed at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

CVE-2026-21933: Oracle Java SE and GraalVM networking data manipulation

Q: Is there a fix for CVE-2026-21933?

No fixed version is recorded yet. Check the vendor's advisory in the references below. If you run it, Junglewise drafts a mitigation that fits your setup and applies it once you approve, with senior security engineers behind it.

Q: How is CVE-2026-21933 attacked?

It is attacked over the network, in a software library.

Q: Am I affected by CVE-2026-21933?

Check whether you run Oracle GraalVM Enterprise Edition, Oracle Graalvm For Jdk, Oracle Java SE or one of the others listed at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

CVE-2026-21933 · Severity: medium · CVSS 6.1 · Published 2026-01-20

A vulnerability in the networking component of Oracle Java and GraalVM could allow an attacker to read or modify certain data. This issue is particularly relevant for systems that run untrusted code from the internet or use web services to process external data. Successful exploitation requires a user to perform an action, such as clicking a link or interacting with a malicious application, and could impact other software relying on the Java environment.

Technologies: Oracle GraalVM Enterprise Edition, Oracle Graalvm For Jdk, Oracle Java SE, Siemens SIMATIC CN 4100. Vendors: Oracle, Siemens.

Quick answers

Is CVE-2026-21933 exploited in the wild?: No. Junglewise Threat Intelligence has no report of CVE-2026-21933 being exploited in the wild.
How severe is CVE-2026-21933?: Medium severity, with a CVSS score of 6.1, published 20 January 2026.
Which products and versions are affected?: Oracle GraalVM Enterprise Edition 21.3.16; Oracle Graalvm For Jdk 17.0.17, 21.0.9; Oracle Java SE 8u471, 8u471-b50, 8u471-perf, 11.0.29, 17.0.17, 21.0.9, 25.0.1; Siemens SIMATIC CN 4100 All versions < V5.0.
Is there a fix for CVE-2026-21933?: No fixed version is recorded yet. Check the vendor's advisory in the references below. If you run it, Junglewise drafts a mitigation that fits your setup and applies it once you approve, with senior security engineers behind it.
How is CVE-2026-21933 attacked?: It is attacked over the network, in a software library.
Am I affected by CVE-2026-21933?: Check whether you run Oracle GraalVM Enterprise Edition, Oracle Graalvm For Jdk, Oracle Java SE or one of the others listed at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

Technical details

This vulnerability exists in the Networking component of Oracle Java SE and GraalVM. It is an easily exploitable flaw that allows an unauthenticated attacker with network access via multiple protocols to compromise the environment, provided there is human interaction (User Interaction: Required). The vulnerability is notable for a 'Scope Change' (S:C), meaning an exploit can impact components beyond the immediate Java runtime. It specifically affects Java deployments that run untrusted code, such as sandboxed Java Web Start applications or applets, and can be triggered through APIs used by web services. Successful exploitation results in unauthorized read, update, insert, or delete access to a subset of accessible data. Oracle addressed this in the January 2026 Critical Patch Update.

Affected products

Oracle Java SE 8u471, 8u471-b50, 8u471-perf, 11.0.29, 17.0.17, 21.0.9, 25.0.1
Oracle GraalVM for JDK 17.0.17, 21.0.9
Oracle GraalVM Enterprise Edition 21.3.16
Siemens SIMATIC CN 4100 All versions < V5.0

Timeline

2026-01-20: disclosed: Initial disclosure by Oracle
2026-01-20: advisory: Oracle January 2026 Critical Patch Update released
2026-05-12: advisory: Siemens published advisory SSA-032379 noting impact on SIMATIC CN 4100

References

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