CVE-2026-44914: Apache NiFi Auth Bypass Vulnerability

CVE-2026-44914 Overview

CVE-2026-44914 is a missing authorization vulnerability [CWE-862] affecting Apache NiFi versions 1.12.0 through 2.9.0. The framework fails to verify Restricted component permissions when users replace Process Groups containing extension components annotated as Restricted. A user holding general write access can introduce components that require elevated privileges, bypassing the intended Restricted authorization boundary. Apache NiFi installations that do not implement specific authorization for Restricted components are not affected, since write permissions act as the security boundary in those deployments. The Apache NiFi project addresses the issue in version 2.9.0 by removing Restricted status authorization from the framework.

Critical Impact
Authenticated users with general write access can deploy components requiring Restricted privileges, expanding their effective permissions across the dataflow platform.

Affected Products

Apache NiFi 1.12.0 through 1.x releases
Apache NiFi 2.0.0 through 2.8.x releases
Deployments enforcing Restricted component authorization policies

Discovery Timeline

2026-06-22 - CVE-2026-44914 published to NVD
2026-06-24 - Last updated in NVD database

Technical Details for CVE-2026-44914

Vulnerability Analysis

Apache NiFi uses a Restricted annotation to mark extension components that require additional privileges beyond standard write access. Examples include components capable of executing operating system commands, accessing local file systems, or interacting with sensitive credentials. The framework normally checks the caller's permission to use Restricted components before instantiation.

The Process Group replacement workflow skips this check. When a user submits a request to replace an existing Process Group with a new flow definition, the framework validates write permissions on the target group but does not iterate the included extension components for Restricted status. An authenticated user with write access can therefore embed Restricted components inside a replacement Process Group payload and have them deployed without holding the required Restricted privilege.

The vulnerability is categorized under [CWE-862: Missing Authorization]. It does not require user interaction and is exploitable over the network against the NiFi REST API.

Root Cause

The framework's authorization layer enforces Restricted component policies on direct component creation endpoints but omits equivalent checks in the Process Group replacement code path. The replacement handler treats the operation as a single write action against the parent group rather than evaluating each contained component against the caller's Restricted policy grants.

Attack Vector

An authenticated user submits a Process Group replacement request through the NiFi REST API. The replacement payload contains one or more extension components carrying the Restricted annotation. The framework accepts the request based on write permissions alone, instantiating the Restricted components under the calling user's session. The attacker can then leverage those components to execute privileged operations such as shell command execution or arbitrary file access on the NiFi host.

No verified proof-of-concept code is published. See the Apache Mailing List Thread and the OpenWall OSS Security Update for vendor details.

Detection Methods for CVE-2026-44914

Indicators of Compromise

Process Group replacement API calls (PUT /nifi-api/process-groups/{id}/flow-contents) originating from accounts that lack Restricted component policies
Newly instantiated components carrying the Restricted annotation in flow audit logs without a corresponding Restricted policy grant for the creator
Unexpected execution of ExecuteStreamCommand, ExecuteProcess, GetFile, or other Restricted processors after a Process Group replacement event

Detection Strategies

Correlate NiFi audit log entries for flow replacement actions with the user's assigned Restricted component policies in the authorizer configuration
Alert on creation events where a component's class is annotated Restricted but the originating user is not granted the restricted-components policy
Review NiFi provenance data for command execution or filesystem access from processors that were added through a Process Group replacement

Monitoring Recommendations

Forward nifi-user.log and nifi-app.log to a central log platform and retain flow modification events for forensic review
Baseline expected Process Group replacement activity per user role and alert on deviations
Monitor the NiFi host for child processes spawned by the NiFi JVM that were not present prior to recent flow changes

How to Mitigate CVE-2026-44914

Immediate Actions Required

Upgrade Apache NiFi to version 2.9.0, which removes framework-level Restricted status authorization and resolves the missing check
Audit existing user and group policies to identify accounts with general write access on Process Groups and validate that access is still required
Review recent Process Group replacement activity for unauthorized introduction of Restricted components

Patch Information

Apache NiFi 2.9.0 is the fixed release. The project announcement is available in the Apache Mailing List Thread. Operators running 1.12.0 through 2.8.x should plan an upgrade path that accounts for breaking changes between the 1.x and 2.x branches.

Workarounds

Restrict write access on Process Groups to a minimal set of trusted operators until the upgrade is applied
Remove Restricted component policies that grant the false sense of a stronger boundary, since general write access is equivalent to Restricted access on affected versions
Place NiFi behind a network boundary that limits REST API access to authenticated administrative networks only

bash

# Verify the running Apache NiFi version
${NIFI_HOME}/bin/nifi.sh status
grep -E "nifi.version" ${NIFI_HOME}/conf/nifi.properties

# Review users granted write access to root Process Group
cat ${NIFI_HOME}/conf/authorizations.xml | \
  grep -B2 -A2 'resource="/process-groups/'