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A vulnerability has been disclosed that potentially impacts organizations using Apache NiFi to manage data pipelines.
The issue could allow lower-privileged users to modify restricted components within a data flow due to missing authorization checks.
“The missing authorization requires a more privileged user to add a restricted component to the flow configuration, but permits a less privileged user to make property configuration changes,” said Apache in its security advisory.
How CVE-2026-25903 Bypasses NiFi Authorization
CVE-2026-25903 stems from a gap in Apache NiFi’s authorization model related to components marked as “Restricted.”
In NiFi, restricted components require elevated privileges to be added to a data flow because they may execute system-level commands or perform sensitive processing actions.
This design is intended to ensure that only trusted users can introduce high-impact components into a workflow.
The issue arises after a restricted component has already been added.
While NiFi correctly enforced elevated permissions during the initial creation of the component, it did not revalidate restricted permissions when configuration properties for that component were later updated.
As a result, a privileged user was required to add the restricted component to the flow, but once it existed, a lower-privileged user could modify its settings without additional authorization checks.
This behavior effectively creates an authorization bypass.
Although the vulnerability does not enable remote code execution or a classic privilege escalation chain, it weakens established permission boundaries within the platform.
A user with limited access could alter processor behavior, modify data routing logic, or change how information is handled within a workflow, potentially affecting data integrity or compliance controls.
Apache notes that deployments without differentiated authorization levels for restricted components are less exposed, as standard write permissions act as the primary security boundary in those environments.
However, organizations that rely on granular role-based access control (RBAC) policies to separate duties around restricted components face higher risk if running affected versions.
The vulnerability impacts Apache NiFi versions 1.1.0 through 2.7.2 and has been addressed in version 2.8.0.
At the time of the advisory’s publication, there were no reports of active exploitation or publicly available proof-of-concept code.
Reducing Risk from NiFi Authorization Flaws
Remediating CVE-2026-25903 should go beyond just installing the latest update.
Organizations should also review and strengthen access controls, monitoring practices, and change management processes within their NiFi environments.
Since the issue involves authorization around restricted components, it is important to reassess permission boundaries and oversight of workflow modifications.
- Patch to the latest version of Apache and ensure restricted component updates enforce proper authorization checks.
- Review and tighten role-based access controls to enforce least privilege, including regular access recertification and validation of restricted component permissions.
- Audit existing data flows and enable version control through NiFi Registry to track configuration changes and quickly roll back unauthorized modifications.
- Monitor logs and integrate NiFi with SIEM tools to detect unusual processor updates, privilege misuse, or suspicious API activity.
- Strengthen authentication by integrating centralized identity management, enforcing MFA for administrative users, and limiting or disabling local accounts.
- Restrict network and API access to NiFi through segmentation, VPN or zero-trust controls, and scoped API tokens to reduce exposure.
- Test incident response plans that include playbooks for investigating unauthorized configuration changes and restoring trusted flow states.
Collectively, these steps can help organizations strengthen authorization controls, improve visibility into configuration changes, and reduce the risk of unauthorized modifications within Apache NiFi environments.
CVE-2026-25903 highlights how gaps in authorization logic can impact the reliability of data workflows.
Although there are no reports of active exploitation, organizations using Apache NiFi should apply the update and review their access control configurations to confirm that permission boundaries are working as expected.
Vulnerabilities like this reinforce why organizations are leveraging zero-trust solutions to continuously verify access and strengthen authorization controls across systems.
