PaperCut NG/MF Missing Authentication for Critical Function Vulnerability
PaperCut — PaperCut MF/NG
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.
9.8
0.8%
Vector breakdown
- Attack vector
- Network
- Attack complexity
- Low
- Privileges required
- None
- User interaction
- None
- Scope
- Unchanged
- Confidentiality
- High
- Integrity
- High
- Availability
- High
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
- Published
- Aug 28, 2026
- Modified
- Sep 14, 2026
- Added to KEV
- Aug 31, 2026
- Federal patch due
- Sep 14, 2026
CISA required action
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.
Weakness classification
Affected packages
Proof-of-concept & exploitation references
2 foundWeaponization
Public repositories whose name or description references CVE-2026-81578, found via a live GitHub search at request time. These are community-sourced signals, not a verified working exploit — cross-check each one before relying on it, and treat higher star counts and recent activity as (weak) corroboration, not proof.
- yora1928/PaperCut-CVE-2026-81578-82078★ 4
Security research tool for PaperCut CVE-2026-81578 & CVE-2026-82078
updated Sep 9, 2026
- virologi-info/papercut-toolkit★ 2
#PaperCut CVE-2026-81578 + CVE-2026-82078 Defense Toolkit 2 3 A **defensive** toolkit to check and understand exposure to the chained
updated Sep 5, 2026
References
Frequently asked questions
What is CVE-2026-81578?
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.
How severe is CVE-2026-81578?
CVE-2026-81578 has a CVSS base score of 9.8 out of 10 (CVSS 3.1).
Is CVE-2026-81578 actively exploited in the wild?
Yes. CVE-2026-81578 is listed in the CISA Known Exploited Vulnerabilities (KEV) catalog, added Aug 31, 2026, meaning CISA has confirmed evidence of active exploitation.
What is the EPSS score for CVE-2026-81578?
0.8% - meaning FIRST.org's EPSS model estimates a 0.8% probability this vulnerability will be exploited in the wild within 30 days (53% percentile among all scored CVEs).
Is there exploit tooling available for CVE-2026-81578?
Yes - a public Nuclei template referencing CVE-2026-81578 exist in public repositories we checked. We also found 2 public GitHub repositories referencing this CVE.
What type of vulnerability is CVE-2026-81578?
CVE-2026-81578 is classified under CWE-305 (CWE-305 Authentication bypass by primary weakness).
Cross-checked against
Impactr finds and proves whether CVE-2026-81578 — or flaws like it — are actually reachable in your own web apps and APIs, with a reproducible exploit as evidence.