How severe is CVE-2026-73866?

CVE-2026-73866 has a CVSS 3.x base score of 9.1, rated critical severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability none.

Is CVE-2026-73866 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (35th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2026-73866?

CVE-2026-73866 affects Oracle Helidon. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2026-73866?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its critical severity, prioritise patching exposed systems.

When was CVE-2026-73866 published?

CVE-2026-73866 was published on 2026-08-18 and last updated on 2026-08-28.

CVE-2026-73866

CVE-2026-73866 is a critical-severity vulnerability in Oracle Helidon with a CVSS 3.x base score of 9.1. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-284.

Key facts

Severity: Critical (CVSS 3.x base score 9.1)
EPSS exploit prediction: 0% (35th percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-284
Affected product: Oracle Helidon
Published: 2026-08-18
Last modified: 2026-08-28

Description

Vulnerability in the Helidon product of Oracle Fusion Middleware (component: Imperative Web Server). Supported versions that are affected are 4.0.0-4.4.1. Easily exploitable vulnerability allows unauthenticated attacker with network access via HTTP to compromise Helidon. Successful attacks of this vulnerability can result in unauthorized creation, deletion or modification access to critical data or all Helidon accessible data as well as unauthorized access to critical data or complete access to all Helidon accessible data. CVSS 3.1 Base Score 9.1 (Confidentiality and Integrity impacts). CVSS Vector: (CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N).

Frequently asked questions

What is CVE-2026-73866?: Vulnerability in the Helidon product of Oracle Fusion Middleware (component: Imperative Web Server). Supported versions that are affected are 4.0.0-4.4.1. Easily exploitable vulnerability allows unauthenticated attacker with network access via HTTP to compromise Helidon. Successful attacks of this vulnerability can result in unauthorized creation, deletion or modification access to critical data or all Helidon accessible data as well as unauthorized access to critical data or complete access to all Helidon accessible data. CVSS 3.1 Base Score 9.1 (Confidentiality and Integrity impacts). CVSS Vector: (CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N).
How severe is CVE-2026-73866?: CVE-2026-73866 has a CVSS 3.x base score of 9.1, rated critical severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability none.
Is CVE-2026-73866 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (35th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2026-73866?: CVE-2026-73866 affects Oracle Helidon. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2026-73866?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its critical severity, prioritise patching exposed systems.
When was CVE-2026-73866 published?: CVE-2026-73866 was published on 2026-08-18 and last updated on 2026-08-28.

References

https://www.oracle.com/security-alerts/cspuaug2026.html

Affected products (1)

cpe:2.3:a:oracle:helidon:4.5.0:*:*:*:*:*:*:*

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