# CVE-2026-91411: Oracle Java SE JGSS denial of service and data access

Source: https://junglewise.ai/threats/cve-2026-91411-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-2026-91411 · Severity: medium · CVSS 6.5 · Published 2026-10-20

Oracle Java SE, GraalVM for JDK, and GraalVM Enterprise Edition contain a vulnerability in the JGSS (Java Generic Security Service) component that can be exploited by a remote attacker over the network. Exploitation can cause the Java runtime to hang or crash repeatedly, disrupting services, and may allow unauthorized modification or deletion of accessible data when the vulnerable APIs are used in applications like web services.

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-2026-91411 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-91411 being exploited in the wild.

**How severe is CVE-2026-91411?** Medium severity, with a CVSS score of 6.5, 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.

**Is there a fix for CVE-2026-91411?** 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-2026-91411 attacked?** It is attacked over the network, in a software library.

**Am I affected by CVE-2026-91411?** 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 JGSS component allows unauthenticated remote attackers to achieve denial of service (hang/crash) and limited data integrity compromise through multiple protocols. The flaw is exploitable via APIs in JGSS when invoked by applications such as web services that process untrusted input, and also affects Java Web Start applets and sandboxed Java applets that load untrusted code.

## Affected products

- Oracle Java SE 8u503, 8u503-perf, 11.0.32.1
- 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)

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- [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)