PaperCut MF/NG: Authentication Bypass

MITRE NVD CVE.ORG JSON API

Summary

CVECVE-2026-81578
StatePUBLISHED
AssignerPaperCut
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-08-28 16:18:29 UTC
Updated2026-09-14 00:16:56 UTC
DescriptionAn 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.

Risk And Classification

Primary CVSS: v4.0 8.8 HIGH from eb41dac7-0af8-4f84-9f6d-0272772514f4

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

EPSS: 0.032900000 probability, percentile 0.878530000 (date 2026-09-16)

CISA KEV: Listed on 2026-08-31; due 2026-09-14; ransomware use Unknown

Problem Types: CWE-305 | CWE-305 CWE-305 Authentication bypass by primary weakness

VersionSourceTypeScoreSeverityVector
4.0eb41dac7-0af8-4f84-9f6d-0272772514f4Secondary8.8HIGHCVSS: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/C...
4.0CNACVSS8.8HIGHCVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:L/VI:H/VA:L/SC:N/SI:N/SA:N
3.1[email protected]Primary9.8CRITICALCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

CVSS v4.0 Breakdown

Attack Vector
Network
Attack Complexity
Low
Attack Requirements
None
Privileges Required
None
User Interaction
None
Confidentiality
Low
Integrity
High
Availability
Low
Sub Conf.
None
Sub Integrity
None
Sub Availability
None

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

CVSS v3.1 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

CISA Known Exploited Vulnerability

VendorPaperCut
ProductNG/MF
NamePaperCut NG/MF Missing Authentication for Critical Function Vulnerability
Required ActionApply 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.
Noteshttps://www.papercut.com/kb/Main/security-bulletin-27-aug-2026-urgent-security-advisory/ ; BOD 26-04: https://www.cisa.gov/news-events/directives/bod-26-04-prioritizing-security-updates-based-risk ; Forensics Triage Requirements: https://www.cisa.gov/news-events/directives/bod-26-04-implementation-guidance-prioritizing-security-updates-based-risk ; https://nvd.nist.gov/vuln/detail/CVE-2026-81578

NVD Known Affected Configurations (CPE 2.3)

TypeVendorProductVersionUpdateEditionLanguage
Application Papercut Papercut Mf All All All All

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA PaperCut PaperCut MF/NG affected 24.1.10 semver Not specified
CNA PaperCut PaperCut MF/NG affected 25.0.0 25.0.13 semver Not specified
CNA PaperCut PaperCut MF/NG affected 26.0.0 26.0.5 semver Not specified

References

ReferenceSourceLinkTags
www.papercut.com/kb/Main/security-bulletin-27-aug-2026-urgent-security-advisory eb41dac7-0af8-4f84-9f6d-0272772514f4 www.papercut.com Patch, Vendor Advisory
github.com/rapid7/metasploit-framework/pull/21842 134c704f-9b21-4f2e-91b3-4a467353bcc0 github.com Issue Tracking, Patch
www.cisa.gov/known-exploited-vulnerabilities-catalog 134c704f-9b21-4f2e-91b3-4a467353bcc0 www.cisa.gov Patch, Third Party Advisory, US Government Resource
CVE Program record CVE.ORG www.cve.org canonical
NVD vulnerability detail NVD nvd.nist.gov canonical, analysis
CISA Known Exploited Vulnerabilities catalog CISA www.cisa.gov kev

Additional Advisory Data

SourceTimeEvent
ADP2026-08-28T00:00:00.000ZCVE-2026-81578 added to CISA KEV

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