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

Published · last modified .

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.

EPSS exploit prediction

EPSS: 0.007 (51.2th percentile), scored .

Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 51st percentile — 51.2% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS trend (30 days)EPSS over the last 30 days for CVE-2026-18265: held from 0.007 to 0.007.

EPSS over last 30 days · oldest: 0.007 · newest: 0.007 · change: 0.000

Affected products

Weakness classification (CWE)

References

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.