PaperCut MF/NG: Authentication Bypass
Prioritize patching. It under exploitation confirmed by CISA and has a public proof of concept.
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.
PaperCut's web management interface has a flaw that allows attackers to perform admin actions without logging in. By sending specially crafted requests, an attacker can bypass the login check and modify system settings.
An improper access control vulnerability in PaperCut MF/NG web management interface permits unauthenticated remote attackers to invoke administrative backend functions before authentication validation completes (CWE-305). The vulnerability enables unauthorized modification of system configurations through direct HTTP requests targeting admin endpoints.