# CVE-2026-91484: Oracle Java SE Java plugin sandbox escape

Source: https://junglewise.ai/threats/cve-2026-91484-vulnerability-in-oracle-java-se-component-java-plugin-supported  
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-2026-91484 · Severity: high · CVSS 7.5 · Published 2026-10-20

Oracle Java SE contains a vulnerability in its Java plugin component that allows a low-privileged local attacker to break out of the Java security sandbox and access sensitive data on the system. This vulnerability primarily affects Java applications running on client endpoints, such as web-start applications or browser applets that load untrusted code from the internet. An exploit could enable unauthorized access to, modification of, or deletion of critical data that the compromised Java process can reach.

Technologies: [Oracle Java SE](https://junglewise.ai/threats/technologies/java-se). Vendors: [Oracle](https://junglewise.ai/threats/vendors/oracle).

## Quick answers

**Is CVE-2026-91484 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-91484 being exploited in the wild.

**How severe is CVE-2026-91484?** High severity, with a CVSS score of 7.5, published 20 October 2026.

**Which products and versions are affected?** Oracle Java SE 8u503, 8u503-perf.

**Is there a fix for CVE-2026-91484?** 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-2026-91484 attacked?** It is attacked with local access, in a software library.

**Am I affected by CVE-2026-91484?** Check whether you run 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

The Java plugin component in Oracle Java SE versions 8u503 and 8u503-perf is vulnerable to a sandbox escape triggered by a local attacker with logon access. The vulnerability requires high complexity to exploit but requires no user interaction and results in scope change, meaning the compromise can impact systems beyond the Java runtime itself. Successful exploitation grants unauthorized read and write access to data accessible by the Java process.

## Affected products

- Oracle Java SE 8u503, 8u503-perf

## 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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