# CVE-2026-91463: Oracle Java SE JGSS information exposure with user interaction

Source: https://junglewise.ai/threats/cve-2026-91463-vulnerability-in-the-oracle-java-se-oracle-graalvm-for-jdk-oracle  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-10-20. Updated: 2026-10-20  
License: CC BY 4.0 with a link back

CVE-2026-91463 · Severity: medium · CVSS 5.3 · Published 2026-10-20

Oracle Java SE is widely used to run Java applications, including web-based programs downloaded from the internet. A vulnerability in the JGSS security component allows an attacker to trick a user into running malicious code that bypasses the Java sandbox and exposes sensitive data. This primarily affects Java Web Start applications and Java applets that execute untrusted code.

Technologies: [Oracle GraalVM Enterprise Edition](https://junglewise.ai/threats/technologies/graalvm-enterprise-edition), [Oracle Graalvm For Jdk](https://junglewise.ai/threats/technologies/graalvm-for-jdk), [Oracle Java SE](https://junglewise.ai/threats/technologies/java-se). Vendors: [Oracle](https://junglewise.ai/threats/vendors/oracle).

## Quick answers

**Is CVE-2026-91463 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-91463 being exploited in the wild.

**How severe is CVE-2026-91463?** Medium severity, with a CVSS score of 5.3, 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-2026-91463?** 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-2026-91463 attacked?** It is attacked over the network, in a software library.

**Am I affected by CVE-2026-91463?** 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 in the Java Generic Security Service (JGSS) component affects multiple Java SE releases and GraalVM distributions. The vulnerability requires network access and user interaction (human-initiated action) to trigger. Successful exploitation results in unauthorized read access to sensitive data accessible to the Java process, without integrity compromise or availability impact.

## 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](https://www.oracle.com/security-alerts/cpuoct2026.html)

## Related threats

- [Oracle Java SE JSSE protocol handling vulnerability](https://junglewise.ai/threats/cve-2026-114820-vulnerability-in-the-oracle-java-se-oracle-graalvm-for-jdk)
- [Oracle Java SE JSSE remote data exposure and modification](https://junglewise.ai/threats/cve-2026-91403-vulnerability-in-the-oracle-java-se-oracle-graalvm-for-jdk-oracle)
- [Oracle Java SE compiler vulnerability in data access](https://junglewise.ai/threats/cve-2026-91487-vulnerability-in-oracle-java-se-component-compiler-supported)
- [Oracle Java SE Java plugin sandbox escape](https://junglewise.ai/threats/cve-2026-91484-vulnerability-in-oracle-java-se-component-java-plugin-supported)
- [Oracle Java SE JGSS information disclosure](https://junglewise.ai/threats/cve-2026-91464-vulnerability-in-the-oracle-java-se-oracle-graalvm-for-jdk-oracle)