Auth bypass in Apache Nifi

CVE-2026-81866

Apache NiFi 2.9.0 through 2.11.0 provide Connector configuration update and verification REST API methods that do not enforce authorization checking on Assets and Secrets referenced in proposed configuration. Updating or verifying a Connector configuration step can apply Asset and Secret references, but framework authorization was limited to write privileges on the Connector itself. As a result of the missing authorization, an authenticated user authorized to modify a Connector, but not authorized to read a referenced Parameter Provider, could apply Secret values backed by that Parameter Provider. The same methods also accepted Asset identifiers without verifying that the Asset belonged to the Connector being configured. Apache NiFi installations that do not implement different levels of authorization across Connectors and Parameter Providers are not subject to this vulnerability, because the framework enforces write permissions on the Connector as the security boundary. Upgrading to Apache NiFi 2.12.0 is the recommended mitigation, which authorizes read access to referenced Parameter Providers and verifies Connector ownership of referenced Assets during configuration update and verification.

Vulnerability class: Broken Access Control

Published · last modified .

CVSS v3 metric

CVSS v3 base score 4.3 (Medium). Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:L/A:N.

EPSS exploit prediction

EPSS: 0.006 (46.9th percentile), scored .

Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 47th percentile — 46.9% 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-2026-81866: held from 0.006 to 0.006.

EPSS over last 30 days · oldest: 0.006 · newest: 0.006 · change: 0.000

Affected products

Weakness classification (CWE)

References

Frequently asked questions

What is CVE-2026-81866?
CVE-2026-81866 is a medium-severity vulnerability in Apache Nifi, classified under Missing Authorization. CVSS score: 4.3/10. Published 2026-09-16.
How severe is CVE-2026-81866?
Medium severity. CVSS v3 base score is 4.3 out of 10.