CVE-2026-81578
Published 2026-08-28 · Updated 2026-09-14 · Source eb41dac7-0af8-4f84-9f6d-0272772514f4
Summary
CVE-2026-81578 is a critical-severity (CVSS 9.8) vulnerability in PaperCut NG/MF. CISA added it to the Known Exploited Vulnerabilities catalog on August 31, 2026, which means exploitation in the wild has been confirmed; US federal agencies had to remediate it by September 14, 2026. CISA does not currently list it as used in ransomware campaigns. PaperCut has 5 vulnerabilities in the KEV catalog, 2 of them linked to ransomware.
All 5 known-exploited PaperCut vulnerabilities →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.
CVSS vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
CISA Known-Exploited Vulnerability
Product: PaperCut — NG/MF
Name: PaperCut NG/MF Missing Authentication for Critical Function Vulnerability
Date added: 2026-08-31 · Due: 2026-09-14
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.