What is CVE-2026-18265?

CVE-2026-18265 is a critical-severity vulnerability in Osnexus Quantastor, classified under Missing Authentication for Critical Function. CVSS score: 9.8/10. Published 2026-08-20.

How severe is CVE-2026-18265?

Critical severity. CVSS v3 base score is 9.8 out of 10.

Auth bypass in Osnexus Quantastor

CVE-2026-18265

OSNEXUS QuantaStor Missing Authentication Remote Code Execution Vulnerability. This vulnerability allows remote attackers to execute arbitrary code on affected installations of OSNEXUS QuantaStor. Authentication is not required to exploit this vulnerability. The specific flaw exists within the configuration of Kapacitor. The issue results from the lack of authentication prior to allowing access to functionality. An attacker can leverage this vulnerability to execute code in the context of root. Was ZDI-CAN-30036.

Vulnerability class: Broken Authentication

CVSS v3 metric

CVSS v3 base score 9.8 (Critical). Vector: CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H.

Affected products

Osnexus Quantastor — versions 6.7.3.010+9c965a6414

Weakness classification (CWE)

CWE-306 — Missing Authentication for Critical Function

References

zdi-disclosures@trendmicro.com (x_research-advisory)

Frequently asked questions

What is CVE-2026-18265?: CVE-2026-18265 is a critical-severity vulnerability in Osnexus Quantastor, classified under Missing Authentication for Critical Function. CVSS score: 9.8/10. Published 2026-08-20.
How severe is CVE-2026-18265?: Critical severity. CVSS v3 base score is 9.8 out of 10.