PaperCut · NG/MF
CVE-2026-81578
PaperCut MF/NG: Authentication Bypass
What it is
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.
CISA: PaperCut NG/MF contains a missing authentication for critical function vulnerability which allows an unauthenticated remote attacker to modify certain system configurations. This vulnerability can be chained with CVE-2026-82078.
What to do
Apply mitigations in accordance with vendor instructions, ensuring compliance with CISA’s BOD 26-04 Prioritizing Security Updates Based on Risk (see URL in Notes) guidance and CISA’s “Forensics Triage Requirements” (see URL in Notes). Follow applicable BOD 26-04 guidance for cloud services or discontinue use of the product if mitigations are unavailable. Stakeholders are responsible for evaluating each asset's internet exposure and ensuring adherence to BOD 26-04 patching guidelines.
Deadline for US federal agencies: September 14, 2026
More exploited flaws from PaperCut
| Added | Vulnerability | Product | Severity | Attack chance |
|---|---|---|---|---|
| Aug 31, 2026 | Unsafe Reflection | NG/MF | Critical 9.4 | 61% |
| Apr 20, 2026 | Improper Authentication | NG/MF | High 8.2 | 78% |
| Jul 28, 2025 | Cross-Site Request Forgery (CSRF) | NG/MF | High 8.4 | 29% |
| Apr 21, 2023 | Improper Access Control | MF/NG | Critical 9.8 | >99.9% |
Sources: Known Exploited Vulnerabilities (CISA, public domain), CVE records (cve.org) and EPSS (FIRST). The chance of attacks is the EPSS estimate that someone will try to exploit the flaw in the next 30 days.