CVE-2026-73935 in Helidon
Summary
by MITRE • 08/19/2026
Vulnerability in the Helidon product of Oracle Fusion Middleware (component: Imperative Web Server). The supported version that is affected is 4.5.1. 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 • 08/19/2026
The identified vulnerability resides within the Imperative Web Server component of Oracle Fusion Middleware Helidon, specifically affecting version 4.5.1. This security flaw is classified as a high-severity issue with a CVSS v3.1 base score of 7.5, indicating significant risk to system availability. The primary characteristic of this vulnerability is that it allows for exploitation by an unauthenticated attacker who requires only network access via the HTTP/2 protocol. Unlike vulnerabilities that compromise data integrity or confidentiality, this specific flaw targets the operational stability of the web server infrastructure, leading directly to service disruption rather than unauthorized data access or modification.
From a technical perspective, the vulnerability enables an attacker to trigger conditions within the Helidon Imperative Web Server that result in either a hang or a frequently repeatable crash. This behavior constitutes a complete denial-of-service condition where the application becomes unresponsive or terminates unexpectedly upon receiving specific malformed or specially crafted HTTP/2 requests. The ease of exploitation is highlighted by the low attack complexity and the absence of any required user interaction or authentication, making it particularly dangerous in public-facing environments where automated scanning tools can rapidly identify and exploit such weaknesses without prior credentials.
The operational impact of this vulnerability is severe for organizations relying on Helidon for their web services. A successful exploit results in a complete denial-of-service, effectively taking the affected application offline. This disruption prevents legitimate users from accessing critical business functions hosted by the middleware. In high-availability architectures, such crashes can lead to cascading failures if load balancers or orchestration systems fail to properly handle node restarts or health check timeouts. The persistent nature of the crash means that repeated attacks can keep the service down indefinitely unless mitigated at a network level or patched immediately.
This vulnerability aligns with CWE-400, which describes uncontrolled resource consumption leading to denial-of-service conditions. Furthermore, in terms of offensive security frameworks such as MITRE ATT&CK, this behavior is consistent with techniques used for Denial of Service attacks where the adversary aims to exhaust system resources or trigger instability rather than establish persistence or escalate privileges. The attack vector falls under network-based exploitation using standard web protocols, specifically leveraging HTTP/2 features that may not be adequately sanitized or handled by the server implementation in version 4.5.1.
To mitigate this risk, immediate action is required to update the Helidon installation to a patched version released by Oracle after the identification of this flaw. Organizations should verify their current deployment versions and apply the relevant security patches provided in official Oracle advisories. In addition to patching, implementing network-level controls such as rate limiting for HTTP/2 connections can help mitigate the impact of automated attacks while updates are being deployed. Web Application Firewalls configured with rulesets that detect anomalous HTTP/2 traffic patterns may also provide a layer of defense against exploitation attempts until the underlying software vulnerability is resolved. Regular monitoring of application logs for signs of unexpected crashes or hangs should be intensified to ensure rapid detection and response if an attack occurs before patching is complete.