# CVE-2026-91487: Oracle Java SE compiler vulnerability in data access

Source: https://junglewise.ai/threats/cve-2026-91487-vulnerability-in-oracle-java-se-component-compiler-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-2026-91487 · Severity: medium · CVSS 4.8 · Published 2026-10-20

Oracle Java SE's compiler component contains a vulnerability that allows unauthenticated attackers on the network to read or modify sensitive data in Java applications. The vulnerability requires difficult-to-exploit conditions and does not cause outages or code execution, but can lead to unauthorized access to application data or business information.

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-2026-91487 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-91487 being exploited in the wild.

**How severe is CVE-2026-91487?** Medium severity, with a CVSS score of 4.8, 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-perf, 11.0.32.1, 17.0.20.1, 21.0.12.1, 25.0.4.1, 27.

**Is there a fix for CVE-2026-91487?** 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-2026-91487 attacked?** It is attacked over the network, in a software library.

**Am I affected by CVE-2026-91487?** 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 vulnerability in the Oracle Java SE Compiler component (CVE-2026-91487) allows unauthenticated network attackers to compromise data confidentiality and integrity through multiple protocols. Exploitation requires supplying malicious data to specific Compiler APIs without using Untrusted Java Web Start applications or applets, and succeeds only under difficult exploitation conditions (CVSS AC:H). Successful exploitation results in unauthorized read and write access to a subset of Java SE accessible data.

## Affected products

- Oracle Java SE 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)

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