9.8

CVE-2026-81578

Warning
Media report

PaperCut MF/NG: Authentication Bypass

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.
Data is provided by the National Vulnerability Database (NVD)
PapercutPapercut Mf Version < 24.1.9
PapercutPapercut Mf Version >= 25.0.2 < 25.0.12
PapercutPapercut Mf Version >= 26.0.2 < 26.0.4
PapercutPapercut Ng Version < 24.1.9
PapercutPapercut Ng Version >= 25.0.2 < 25.0.12
PapercutPapercut Ng Version >= 26.0.2 < 26.0.4
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28.08.2026: CISA Known Exploited Vulnerabilities (KEV) Catalog

PaperCut NG/MF Missing Authentication for Critical Function Vulnerability

Vulnerability

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.

Description

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.

Required actions
EPSS Metrics
Type Source Score Percentile
EPSS FIRST.org 0.39% 0.323
CVSS Metrics
Source Base Score Exploit Score Impact Score Vector string
NIST 9.8 3.9 5.9
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
eb41dac7-0af8-4f84-9f6d-0272772514f4 8.8 0 0
CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:L/VI:H/VA:L/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
CWE-305 Authentication Bypass by Primary Weakness

The authentication algorithm is sound, but the implemented mechanism can be bypassed as the result of a separate weakness that is primary to the authentication error.

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14.09.2026 17:54
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https://www.papercut.com/kb/Main/security-bulletin-27-aug-2026-urgent-security-advisory/
Patch
Vendor Advisory
https://github.com/rapid7/metasploit-framework/pull/21842
Patch
Issue Tracking
https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2026-81578
Patch
Third Party Advisory
US Government Resource