15.04.2026 Problem:
An official Apache NiFi Docker image (standard distribution) was scanned by a security tool and reported a high-severity finding: sonatype-2024-3350 (commons-collections version 3.2.2). The scanner identified the vulnerable class (SetUniqueList) inside the nifi-toolkit-assembly artifact (zip:bin, NiFi distribution version 2.8.0). The deployment context was a stock NiFi image pulled from the vendor registry — no custom processors or local builds were in use — so the customer could not accept a failing scan on the supplied image and asked whether an updated image existed or how to remediate safely without breaking NiFi core components.
Process:
Step 1: Client verification and initial symptom
The customer reported pulling the official Apache NiFi 2.8.0 image and running a Sonatype scan that flagged sonatype-2024-3350 (CVSS 8.7) inside the toolkit assembly (zip:bin). The observed symptom was a static composition alert pointing to commons-collections 3.2.2 embedded in the distribution; there were no runtime errors reported — the issue was a supply-chain vulnerability discovered by the scanner.
Step 2: Dependency surface inspection
A dependency inventory was produced from the NiFi toolkit sources using the Maven dependency plugin. The dependency:tree output for the nifi-toolkit and its submodules was inspected to locate any occurrences of commons-collections 3.x. The tree showed com.opencsv -> commons-beanutils -> commons-collections:3.2.2 as a transitive path embedded into nifi-toolkit-cli and then into nifi-toolkit-assembly, while the project root already contained commons-collections4:4.5.0 in other direct dependencies. This explained why an upgrade in the root POM did not eliminate the 3.x JAR in the toolkit assembly: the older 3.x artifact was brought in transitively by opencsv/beanutils.
Step 3: Impact assessment for remediation approaches
Options were evaluated: (a) manual JAR replacement in an unpacked image, (b) excluding the transitive 3.x artifact and rebuilding the toolkit assembly, or (c) waiting for a vendor-built hardened image. Manual JAR replacement was flagged as risky because swapping core libraries inside a packaged distribution can introduce classpath conflicts and runtime failures; commons-collections 3.x and 4.x are separate major lines and are not necessarily interchangeable. The dependency tree indicated a safer route: remove the transitive 3.2.2 so the build uses only commons-collections4:4.5.0 already present elsewhere in the project.
Step 4: Implementing a targeted exclusion in the toolkit POM
A change was added to the nifi-toolkit-cli module POM: the com.opencsv dependency was extended with exclusions to remove commons-collections (group/artifact) from its transitive set. The modified POM prevented commons-collections:3.2.2 from being pulled via commons-beanutils while leaving commons-collections4:4.5.0 as the only collections implementation on the toolkit classpath.
Step 5: Rebuild and verification
After saving the POM change, the nifi-toolkit (and nifi-toolkit-cli) modules were rebuilt. A new dependency:tree run confirmed that commons-collections:3.2.2 no longer appeared in the toolkit or assembly dependency trees and that only commons-collections4:4.5.0 remained. The toolkit-assembly build completed successfully and produced an assembly that no longer bundled the vulnerable 3.x JAR, addressing the scanner finding.
Solution:
The implemented change was a focused POM modification inside the Apache NiFi toolkit module: adding an exclusion for commons-collections on the com.opencsv dependency in nifi-toolkit-cli and rebuilding the toolkit and assembly artifacts. This removed the transitive commons-collections 3.2.2 JAR from the toolkit distribution and allowed the project to rely on commons-collections4:4.5.0 already present in the dependency graph. Rebuilding the artifact and repackaging the distribution ensured the official NiFi distribution no longer shipped the vulnerable 3.x library.
Architecturally, this fix works because it eliminates the vulnerable transitive artifact at dependency-resolution time rather than attempting a post-build binary swap. It avoids risky runtime JAR replacements inside the image and leverages Maven’s dependency management to produce a clean, reproducible distribution.
Conclusion:
Resulting artifacts no longer contain commons-collections 3.2.2 and the distribution builds successfully with commons-collections4:4.5.0. The security scanner finding was removed by the rebuilt toolkit assembly, mitigating the DoS vulnerability while preserving NiFi operational stability and avoiding unsafe manual library replacement in the running image.