⚠ Reference material — not professional advice. Test in staging, back up first, verify against your specific version. Use your own judgment for your environment.
● High · CVSS 8.7

How to Fix CVE-2026-25903: Critical Vulnerability in Apache NiFi

Other vulnerabilities in the same area that are worth patching alongside this one:

*By Sai Kiran Pandrala*

⚡ At a glance
SeverityCVSS 8.7 - High
Actively exploited?Not currently listed in CISA KEV
Affected1.1.0 < 2.8.0
Fixed inSee vendor advisory
Type (CWE)CWE-862: Missing Authorization

What is CVE-2026-25903?

CVE-2026-25903 is a security flaw in Apache NiFi. Apache NiFi 1.1.0 through 2.7.2 are missing authorization when updating configuration properties on extension components that have specific Required Permissions based on the Restricted annotation. The Restricted annotation indicates additional privileges required to add the annotated component to the flow configuration, but framework authorization did not check restricted status when updating a component previously added.

Why this CVE matters

Unpatched network-facing software is the leading initial-access vector in public breach reporting. Treat any CVSS-9 class flaw on an internet-reachable system as urgent, regardless of whether public exploit code has been observed yet.

For deployments of Apache NiFi that have been exposed to the public internet during the disclosure window, the operating assumption should be that scanning has already happened. Even where exploitation has not been publicly observed, scanning for the vulnerable fingerprint is cheap and routine. Patching closes the door; log review and credential rotation close out the rest of the response.

Am I affected?

You are affected if your installation matches any of these version ranges:

Check your installed version against the list above. If you cannot determine the version, treat the system as affected and follow the upgrade path below.

Run the project-specific version command (for example httpd -v, tomcat version, or check pom.xml / package metadata) and compare against the advisory.

How to fix CVE-2026-25903

  1. Read the vendor advisory in full: https://lists.apache.org/thread/jf6bkt9sk6xvshy8xyxv3vtlxd340345
  2. Upgrade Apache NiFi to the patched build listed in the vendor advisory.
  3. Back up the configuration (and database, where applicable) before upgrading.
  4. Apply the patch in a maintenance window. For HA pairs, upgrade the standby node first, fail over, then upgrade the former primary.
  5. Restart the affected service so the patched binary loads, then verify the new version (see verification section).

Patched-version commands

Vendor advisory: https://lists.apache.org/thread/jf6bkt9sk6xvshy8xyxv3vtlxd340345

Affected: Apache NiFi: 1.1.0 < 2.8.0

Patched in: 2.8.0


# Vendor advisory: https://lists.apache.org/thread/jf6bkt9sk6xvshy8xyxv3vtlxd340345

# Debian / Ubuntu.
sudo apt update
sudo apt install --only-upgrade apache2
sudo systemctl restart apache2

# RHEL / Rocky / AlmaLinux / Fedora (use httpd for Apache).
sudo dnf upgrade httpd
sudo systemctl restart httpd

# Verify the running version matches 2.8.0 from the advisory.
apache2 -v


# Vendor advisory: https://lists.apache.org/thread/jf6bkt9sk6xvshy8xyxv3vtlxd340345
# IIS-hosted equivalent on Windows.
Install-Module PSWindowsUpdate -Force -SkipPublisherCheck -Confirm:$false
Get-WindowsUpdate -AcceptAll -Install -AutoReboot
Restart-WebAppPool -Name "<AppPoolName>"

Verify the fix landed


# Vendor advisory: https://lists.apache.org/thread/jf6bkt9sk6xvshy8xyxv3vtlxd340345
# Post-patch verification (replace <service> with the real service unit).
journalctl -u <service> --since "10 minutes ago"
dmesg --since "10 minutes ago"

# Re-scan with your vulnerability scanner (Nessus, Qualys, Tenable, OpenVAS).
# It should no longer flag CVE-2026-25903 on the patched target.

If you cannot patch immediately

Restrict access to the management interface to trusted internal IP addresses only. Block public access at the firewall and require VPN for any remote administration. Apply the patch as soon as a maintenance window allows.

How to verify the fix worked

If your installation was internet-reachable during the disclosure window, treat log review as part of the remediation rather than an optional follow-up. Look for log entries that do not match your normal request patterns, especially repeated requests to the same uncommon endpoint, and any administrative changes you cannot tie back to a known operator.

Frequently asked questions

Is CVE-2026-25903 being exploited in the wild?

Public exploitation has not been confirmed by CISA at the time of writing. Treat the patch as time-sensitive anyway; reports often lag actual abuse.

Will a WAF or IDS rule fully mitigate CVE-2026-25903?

No. Network-layer filters can reduce noise and slow opportunistic scanners, but they will not stop a determined attacker. The vendor patch is the only durable fix.

How long should I plan for the upgrade?

Typical vendor-documented upgrade windows for Apache NiFi run from a few minutes to under an hour depending on cluster size. Test in a staging environment first and follow the vendor's documented HA upgrade order.

References

*This guide was assembled from the official vendor advisory, the NVD record, and the CISA KEV catalog entry on 2026-05-25. Always confirm against the vendor advisory before applying changes in production.*