CVE-2026-73890 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 4.5.0. 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 • 08/19/2026
The identified vulnerability resides within the Imperative Web Server component of Oracle Fusion Middleware Helidon, specifically affecting version 4.5.0. 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 core technical nature of this vulnerability involves an easily exploitable condition that allows unauthenticated attackers to trigger severe service disruptions. Because the attack vector requires only network access via HTTP/2 and no prior authentication or user interaction, the barrier for exploitation is exceptionally low. This characteristic makes it particularly dangerous in public-facing environments where Helidon serves as a web server handling incoming requests from potentially malicious actors on the internet.
From a technical perspective, the vulnerability manifests through improper input validation or state management within the HTTP/2 protocol handler of the Imperative Web Server. When an attacker sends specific malformed or specially crafted HTTP/2 frames, it triggers a logic error that causes the Helidon process to hang or crash repeatedly. This behavior aligns with CWE-400, which describes uncontrolled resource consumption leading to denial-of-service conditions. The repeated nature of the crashes suggests that the flaw is not a one-time exception but rather a consistent failure point in the server's request processing pipeline. Consequently, an attacker can sustainably degrade or completely halt service availability by continuously sending these triggering payloads, effectively rendering the application inaccessible to legitimate users.
The operational impact of this vulnerability is severe due to its direct effect on system availability. A successful exploitation results in a complete denial-of-service (DoS) condition where Helidon becomes unresponsive or crashes repeatedly. This disruption can lead to significant business downtime, loss of revenue, and damage to organizational reputation if the affected service is critical to operations. Since no authentication is required, any entity with network connectivity to the server port hosting Helidon can execute this attack. There are no prerequisites such as valid credentials or user interface interactions, which simplifies automated exploitation tools and increases the likelihood of widespread attacks against vulnerable instances deployed in cloud environments or on-premises data centers without adequate perimeter security controls.
In terms of threat modeling and industry standards, this vulnerability maps to MITRE ATT&CK technique T1499, Endpoint Denial of Service, specifically under the sub-technique for resource exhaustion via application layer attacks. It also relates to CWE-20 Improper Input Validation if the root cause is insufficient sanitization of HTTP/2 frame data. The attack vector falls under Network (AV:N) with Low complexity (AC:L), confirming that sophisticated skills are not required to exploit it. Security teams should prioritize this issue due to its high availability impact and low exploitation difficulty, especially given the prevalence of Helidon in modern microservices architectures where web servers handle substantial traffic volumes.
Mitigation strategies must focus on immediate patching and defensive network controls. The primary remediation is to apply the latest security update provided by Oracle for Helidon version 4.5.0 or upgrade to a newer, patched release that resolves this specific flaw in the Imperative Web Server component. In environments where immediate patching is not feasible due to operational constraints, organizations should implement network-level mitigations such as rate limiting on HTTP/2 connections and deploying Web Application Firewalls (WAF) configured to detect and block anomalous HTTP/2 traffic patterns associated with this vulnerability. Additionally, ensuring that Helidon instances are not directly exposed to untrusted networks without proper authentication or access control lists can reduce the attack surface. Regular security assessments and penetration testing should include specific checks for HTTP/2 protocol handling flaws to identify similar vulnerabilities before they can be exploited in production environments.