PaperCut MF/NG - Authentication Bypass (CVE-2026-81578)
Description
An improper access control vulnerability exists in the web management interface of PaperCut MF and PaperCut NG. Under specific conditions, unauthenticated remote requests targeting administrative functions can trigger backend actions prior to the completion of access validation checks. This allows an unauthenticated remote attacker to modify certain system configurations.
psychologyCrowdSec Analysis
CVE-2026-81578 is a high-severity improper access control vulnerability in the PaperCut MF/NG web management interface. Under specific conditions, unauthenticated remote attackers can bypass access validation and invoke administrative backend actions, potentially modifying system configurations and disrupting or compromising the managed printing environment.
CrowdSec has been tracking this vulnerability and its exploits since 17th of September 2026.
CrowdSec has not observed any significant exploitation activity targeting CVE-2026-81578 across its network. As a result, no community-driven trend analysis is available for this vulnerability at this time.
Attackers target the PaperCut web interface at /app, using Tapestry service requests such as /app?service=page/Error and /app?service=direct/<random>/Home/ConfigEditor/quickFindForm. The exploit abuses a complex-direct request to invoke the privileged ConfigEditor form listener without authentication, typically submitting parameters such as sp, Form0, $TextField, and doQuickFind.
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| Event | Date |
|---|---|
| CVE Published | 2026-08-28 |
| CISA KEV | 2026-08-31 |
| CISA Remediation Deadline | 2026-09-14 |
| Rule Released | 2026-09-17 |
| CrowdSec First Seen | 2026-09-28 |
Remediation & Protection
External References
- https://github.com/rapid7/metasploit-framework/pull/21842
- https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2026-81578
- https://www.papercut.com/kb/Main/security-bulletin-27-aug-2026-urgent-security-advisory/
- https://github.com/projectdiscovery/nuclei-templates/blob/main/http/cves/2026/CVE-2026-81578.yaml