# CVE-2026-101587: Oracle Helidon denial of service in webclient HTTP/1

Source: https://junglewise.ai/threats/cve-2026-101587-vulnerability-in-the-helidon-product-of-oracle-fusion-middleware  
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-2026-101587 · Severity: medium · CVSS 5.3 · Published 2026-10-20

Oracle Helidon is a microservices framework that handles web requests. An unauthenticated attacker can send specially crafted HTTP requests to partially disrupt service availability for applications built with Helidon. This denial-of-service vulnerability requires no authentication and can be triggered remotely over the network.

Technologies: [Oracle Helidon](https://junglewise.ai/threats/technologies/helidon). Vendors: [Oracle](https://junglewise.ai/threats/vendors/oracle).

## Quick answers

**Is CVE-2026-101587 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-101587 being exploited in the wild.

**How severe is CVE-2026-101587?** Medium severity, with a CVSS score of 5.3, published 20 October 2026.

**Which products and versions are affected?** Oracle Helidon 4.0.0 through 4.5.5, 27.0.0.

**Is there a fix for CVE-2026-101587?** 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-2026-101587 attacked?** It is attacked over the network, in a software library.

**Am I affected by CVE-2026-101587?** Check whether you run Oracle Helidon 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 vulnerability exists in the helidon-webclient-http1 component of Helidon and allows an unauthenticated network attacker to trigger a partial denial of service condition. The HTTP/1 webclient does not properly validate or handle certain HTTP requests, allowing remote actors to cause availability impact via network-accessible HTTP. An attacker needs only network access to the HTTP endpoint; no authentication or user interaction is required.

## Affected products

- Oracle Helidon 4.0.0 through 4.5.5, 27.0.0

## 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 Helidon microprofile-security authentication bypass](https://junglewise.ai/threats/cve-2026-101590-vulnerability-in-the-helidon-product-of-oracle-fusion-middleware)
- [Oracle Helidon WebSocket unauthenticated information disclosure](https://junglewise.ai/threats/cve-2026-101588-vulnerability-in-the-helidon-product-of-oracle-fusion-middleware)
- [Oracle Helidon information disclosure in helidon-webclient](https://junglewise.ai/threats/cve-2026-101586-vulnerability-in-the-helidon-product-of-oracle-fusion-middleware)
- [Oracle Helidon CORS authorization bypass in helidon-cors](https://junglewise.ai/threats/cve-2026-101585-vulnerability-in-the-helidon-product-of-oracle-fusion-middleware)
- [Oracle Helidon information disclosure and denial of service in WebSocket client](https://junglewise.ai/threats/cve-2026-101584-vulnerability-in-the-helidon-product-of-oracle-fusion-middleware)