Is CVE-2026-91398 exploited in the wild?

No. Junglewise Threat Intelligence has no report of CVE-2026-91398 being exploited in the wild.

How severe is CVE-2026-91398?

Medium severity, with a CVSS score of 6.8, published 20 October 2026.

Which products and versions are affected?

Oracle GraalVM Enterprise Edition 21.3.19.1.1; Oracle Graalvm For Jdk 17.0.20.1, 21.0.12.1; Oracle Java SE 8u503, 8u503-perf, 11.0.32.1, 17.0.20.1, 21.0.12.1, 25.0.4.1, 27.

Is there a fix for CVE-2026-91398?

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-2026-91398 attacked?

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

Am I affected by CVE-2026-91398?

Check whether you run Oracle GraalVM Enterprise Edition, Oracle Graalvm For Jdk or Oracle Java SE 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-2026-91398: Oracle Java SE networking vulnerability via SOCKS5

CVE-2026-91398 · Severity: medium · CVSS 6.8 · Published 2026-10-20

Oracle Java SE and related products contain a vulnerability in their networking component that can be exploited over the network via SOCKS5 protocol. An attacker with network access can exploit this flaw to compromise data integrity, potentially creating, deleting, or modifying critical data accessible to the Java runtime or applications using it. The vulnerability also affects Java Web Start applications and applets that load untrusted code from the internet.

Technologies: Oracle GraalVM Enterprise Edition, Oracle Graalvm For Jdk, Oracle Java SE. Vendors: Oracle.

Quick answers

Is CVE-2026-91398 exploited in the wild?: No. Junglewise Threat Intelligence has no report of CVE-2026-91398 being exploited in the wild.
How severe is CVE-2026-91398?: Medium severity, with a CVSS score of 6.8, published 20 October 2026.
Which products and versions are affected?: Oracle GraalVM Enterprise Edition 21.3.19.1.1; Oracle Graalvm For Jdk 17.0.20.1, 21.0.12.1; Oracle Java SE 8u503, 8u503-perf, 11.0.32.1, 17.0.20.1, 21.0.12.1, 25.0.4.1, 27.
Is there a fix for CVE-2026-91398?: 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-2026-91398 attacked?: It is attacked over the network, in a software library.
Am I affected by CVE-2026-91398?: Check whether you run Oracle GraalVM Enterprise Edition, Oracle Graalvm For Jdk or Oracle Java SE 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

A difficult-to-exploit vulnerability exists in the Networking component of Oracle Java SE, Oracle GraalVM for JDK, and Oracle GraalVM Enterprise Edition, accessible via SOCKS5 protocol without authentication. The attack has network adjacency requirements and impacts data integrity with scope change, potentially affecting additional downstream products that depend on these Java runtimes. A fix is confirmed to exist per Oracle's security advisory.

Affected products

Oracle Java SE 8u503, 8u503-perf, 11.0.32.1, 17.0.20.1, 21.0.12.1, 25.0.4.1, 27
Oracle GraalVM for JDK 17.0.20.1, 21.0.12.1
Oracle GraalVM Enterprise Edition 21.3.19.1.1

Timeline

2026-10-20: disclosed

References

https://www.oracle.com/security-alerts/cpuoct2026.html

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