# CVE-2026-91453: Oracle Java SE integrity bypass in Lightweight HTTP Server

Source: https://junglewise.ai/threats/cve-2026-91453-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-2026-91453 · Severity: medium · CVSS 5.3 · Published 2026-10-20

Oracle Java SE and GraalVM include a Lightweight HTTP Server component that is vulnerable to unauthorized data modification over the network. An unauthenticated attacker can exploit this without user interaction to alter data accessible to the server, potentially compromising the integrity of applications that rely on this component.

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-2026-91453 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-91453 being exploited in the wild.

**How severe is CVE-2026-91453?** 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, 11.0.32.1, 17.0.20.1, 21.0.12.1, 25.0.4.1, 27.

**Is there a fix for CVE-2026-91453?** 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-2026-91453 attacked?** It is attacked over the network, in a software library.

**Am I affected by CVE-2026-91453?** 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

An integrity bypass vulnerability exists in the Lightweight HTTP Server component of Oracle Java SE and GraalVM. The vulnerability is easily exploitable via network access without authentication or user interaction, affecting the ability to prevent unauthorized updates, inserts, or deletions to accessible data. The attack requires supplying data directly to APIs in the affected component outside of Java Web Start or applet contexts.

## Affected products

- Oracle Java SE 8u503, 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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