IRONSMITHINTEL
CRITICALCVSS9.8
|
Actively Exploited
|CISA KEV|CVE-2023-27350|Auth: none — unauthenticated|Reboot: required|Manual only

PaperCut MF/NG Improper Access Control Vulnerability

PaperCut MF/NG contains an improper access control vulnerability within the SetupCompleted class that allows authentication bypass and code execution in the context of system.

Published Apr 20, 2023 · Updated May 16, 2026
Why patchRisk explained in plain English
Worst-case scenarioIf unpatched

A remote attacker, without authentication, can achieve full data confidentiality loss, arbitrary modification of data, complete denial of service or system unavailability. CISA has confirmed use of this vulnerability in known ransomware campaigns — treat as high priority for remediation. Federal agencies are required to remediate by 2023-05-12 under CISA BOD 22-01.

How the attack worksNo clicks needed

This is a Software Vulnerability (CWE-284) (CWE-284) vulnerability in PaperCut MF/NG. This vulnerability allows remote attackers to bypass authentication on affected installations of PaperCut NG 22.0.5 (Build 63914). Authentication is not required to exploit this vulnerability. The specific flaw exists within the SetupCompleted class. The issue results from improper access control. An attacker can leverage this vulnerability to bypass authentication and execute arbitrary code in the context of SYSTEM. Was ZDI-CAN-18987. Exploitation requires remote network access, low attack complexity, no authentication required, and no user interaction required.

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Phishing link

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Malicious file

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Server compromised

Am I affected?Quick check

Probably yes if any of these apply:

IT Security
Running papercut mf: 8.0 ≤ v < 20.1.7, 21.0.0 ≤ v < 21.2.11, 22.0.0 ≤ v < 22.0.9; papercut ng: 8.0 ≤ v < 20.1.7, 21.0.0 ≤ v < 21.2.11, 22.0.0 ≤ v < 22.0.9
Real-world incidentsWhat we've seen

Used in known ransomware campaigns. Threat-research write-up: http://packetstormsecurity.com/files/172022/PaperCut-NG-MG-22.0.4-Authentication-Bypass.html

How to patch

Manual remediation steps

Apply the Vendor Patch

This vulnerability is in the CISA Known Exploited Vulnerabilities catalog — apply the vendor's security update as soon as possible.

CISA required action: Apply updates per vendor instructions.

References

    1
    Vendor advisory: https://www.papercut.com/kb/Main/PO-1216-and-PO-1219
    1
    NVD entry: https://nvd.nist.gov/vuln/detail/CVE-2023-27350
    1
    CISA KEV: https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2023-27350
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