What is the CVSS score of CVE-2026-73890?

CVE-2026-73890 has a CVSS 3.1 base score of 7.5 (High). CVSS vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H. EPSS exploitation probability: 0.3%.

Which versions of Helidon are affected by CVE-2026-73890?

Oracle Helidon 4.5.0's Imperative Web Server is vulnerable to unauthenticated remote denial-of-service attacks that can crash or indefinitely hang the application server, with no public exploit…

How to fix or mitigate CVE-2026-73890?

Within 24 hours, identify and document all systems running Oracle Helidon 4.5.0 and their network exposure across your infrastructure. Within 7 days, implement HTTP/2-specific rate limiting at load balancer and WAF layers, restrict network access to vulnerable instances via firewall rules and network segmentation, and deploy external DDoS protection services. Over the next 30 days, establish continuous monitoring of Oracle security advisories for patch availability and develop an upgrade plan to Helidon 4.6.0 or later; until a patch is released, run vulnerable services behind a reverse proxy with HTTP/2 request filtering and validation.

Helidon CVE-2026-73890

EUVD-2026-62134 HIGH

Improper Access Control (CWE-284)

2026-08-18 secalert_us@oracle.com

GHSA-99gg-7fw7-27rc

Oracle Authentication Bypass Helidon

7.5

CVSS 3.1 · Vendor: oracle

Severity by source

Vendor (oracle) PRIMARY

7.5 HIGH

AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

vuln.today AI

7.5 HIGH

HTTP/2 endpoint is network-accessible with no authentication or complexity; impact is purely availability (crash or hang) with no confidentiality or integrity effects.

3.1 AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

4.0 AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N

Primary rating from Vendor (oracle).

CVSS VectorVendor: oracle

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Attack Vector

Network

Attack Complexity

Low

Privileges Required

None

User Interaction

None

Scope

Unchanged

Confidentiality

None

Integrity

None

Availability

High

Lifecycle Timeline

Analysis Generated

Aug 18, 2026 - 22:07 vuln.today

CVE Published

Aug 18, 2026 - 21:18 nvd

HIGH 7.5

DescriptionCVE.org

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).

AnalysisAI

Remote denial-of-service in Oracle Helidon 4.5.0's Imperative Web Server component allows unauthenticated network attackers to crash or indefinitely hang the server by sending crafted HTTP/2 traffic. The vulnerability carries a CVSS 7.5 rating with low attack complexity and no credential or interaction requirement, making it trivially scriptable from any network-accessible position. …

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Attack ChainAIDerived

Hypothetical attack flow derived from CVE metadata

Access

Identify Helidon 4.5.0 HTTP/2 endpoint

Delivery

Send crafted HTTP/2 frames

Exploit

Trigger Imperative Web Server processing fault

Execution

Cause server hang or crash

Impact

Repeat to sustain complete DoS

Access

Identify Helidon 4.5.0 HTTP/2 endpoint

Delivery

Send crafted HTTP/2 frames

Exploit

Trigger Imperative Web Server processing fault

Execution

Cause server hang or crash

Impact

Repeat to sustain complete DoS

Vulnerability AssessmentAI

Exploitation	The target must be running Oracle Helidon version 4.5.0 with the Imperative Web Server component deployed and HTTP/2 enabled - HTTP/2 is the explicit and exclusive attack protocol named in Oracle's advisory; the vulnerability is not exercisable over HTTP/1.1. … Additional conditions and limiting factors are described in the full assessment.
Risk Assessment	The CVSS 7.5 vector (AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H) is internally consistent with the advisory description: remotely exploitable with no credentials, no user interaction, and no special preconditions beyond network reachability over HTTP/2. … Full risk analysis with EPSS, KEV, and SSVC signal comparison available after sign-in.
Exploit Scenario	An unauthenticated attacker with network access sends a sequence of crafted HTTP/2 frames - for example, malformed HEADERS, DATA, or SETTINGS frames designed to exploit a parsing fault or unbounded resource allocation in the Imperative Web Server - causing the server process to hang indefinitely or crash. Because the attack requires no credentials, no user interaction, and involves low complexity, it can be scripted for repeated automated triggering, sustaining a complete denial-of-service against any exposed Helidon 4.5.0 endpoint. …
Remediation	Apply Oracle's Critical Patch Update released in August 2026, referenced at https://www.oracle.com/security-alerts/cspuaug2026.html. … Detailed patch versions, workarounds, and compensating controls in full report.