CVE-2026-81578
PaperCut MF/NG: Authentication Bypass
PaperCut NG/MF Missing Authentication for Critical Function Vulnerability is confirmed as actively exploited and is listed in the CISA KEV catalog.
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.
CISA notes
https://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
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.
Severity
CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:L/VI:H/VA:L/SC:N/SI:N/SA:NAffected Products
| Vendor | Product | Affected versions |
|---|---|---|
| PaperCut | PaperCut MF/NG | 0 to <24.1.10 25.0.0 to <25.0.13 26.0.0 to <26.0.5 |
References
1 LinksRecord Details
More from PaperCut
PaperCut MF/NG Improper Access Control Vulnerability
PaperCut NG/MF Improper Authentication Vulnerability
PaperCut MF/NG: Unsafe Dynamic Class Loading in Database Connector
PaperCut MF/NG 22.0.10 (Build 65996 2023-03-27) - Remote code execution via CSRF
Related Tool Categories
Tool categories that test for or protect against this vulnerability class.
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