CVE-2026-101572 in Helidon
Summary
by MITRE • 10/21/2026
Vulnerability in the Helidon product of Oracle Fusion Middleware (component: helidon-webclient-http2). Supported versions that are affected are 4.0.0-4.5.5 and 27.0.0. Easily exploitable vulnerability allows unauthenticated attacker with network access via HTTP/2 to compromise Helidon. Successful attacks of this vulnerability can result in unauthorized ability to cause a hang or frequently repeatable crash (complete DOS) of Helidon. CVSS 3.1 Base Score 7.5 (Availability impacts). CVSS Vector: (CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H).
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Analysis
by VulDB Data Team • 10/21/2026
The identified vulnerability resides within the helidon-webclient-http2 component of Oracle Fusion Middleware's Helidon product line, specifically affecting versions ranging from 4.0.0 through 4.5.5 and version 27.0.0. This security flaw is classified as a critical availability risk due to its potential for causing complete denial of service conditions in supported environments. The vulnerability stems from an implementation error within the HTTP/2 protocol handling logic, which fails to properly manage specific malformed or unexpected request patterns sent by clients utilizing the HTTP/2 transport layer. Because Helidon serves as a high-performance microservices framework often deployed at the edge of enterprise architectures, such failures can have immediate and severe consequences for system stability and service continuity.
From a technical perspective, the flaw allows an unauthenticated attacker with network access to exploit the vulnerability remotely via standard HTTP/2 connections. The attack vector does not require any form of authentication or user interaction, making it particularly dangerous in public-facing deployments where external traffic is routinely processed without prior identity verification. When triggered, the defect causes the Helidon server process to hang or enter a state requiring frequent repetition that leads to a complete crash. This behavior indicates a likely resource exhaustion issue, such as an infinite loop, memory leak, or deadlock condition within the HTTP/2 stream management subsystems. The inability of the application to gracefully handle these specific inputs results in the termination of the server process or its unresponsiveness to legitimate requests.
The operational impact of this vulnerability is severe, primarily categorized under availability impacts with a CVSS 3.1 Base Score of 7.5. A successful exploitation leads to unauthorized ability to cause a hang or frequently repeatable crash, effectively resulting in a complete denial of service for the Helidon instance and any downstream services dependent on it. For organizations relying on Oracle Fusion Middleware for critical business operations, this translates into significant downtime, potential data loss if transactions are interrupted mid-flight, and increased operational costs associated with incident response and recovery efforts. The lack of authentication requirements means that automated scanning tools or malicious actors can easily target vulnerable instances across the internet without needing to bypass access controls first.
In terms of industry standard classifications, this vulnerability aligns closely with CWE-400 Uncontrolled Resource Consumption, as the exploit leverages specific inputs to exhaust system resources such as CPU cycles or memory until the application fails. Furthermore, from a tactical perspective within the MITRE ATT&CK framework, this behavior is consistent with techniques used in Denial of Service attacks where an adversary aims to disrupt service availability rather than compromise data integrity or confidentiality. The network-based nature and lack of user interaction place it firmly within remote exploitation categories that require immediate attention by security operations teams monitoring for anomalous HTTP/2 traffic patterns indicative of such abuse.
To mitigate this risk, organizations running affected versions of Helidon must prioritize applying the latest available patches from Oracle immediately. If patching is not feasible in the short term, network-level controls should be implemented to restrict access to the vulnerable endpoints. This can include configuring web application firewalls or reverse proxies to rate-limit HTTP/2 connections and inspect incoming requests for malformed headers or excessive stream creation that might trigger the flaw. Additionally, enabling strict input validation at the gateway level before traffic reaches the Helidon instance can help filter out malicious payloads designed to exploit this specific weakness. Regular monitoring of server logs for signs of repeated crashes or high resource utilization should also be established to detect potential exploitation attempts early and facilitate rapid incident response.