CVE WatchOct 1, 2026

CVE-2023-27351

PaperCut NG/MF Improper Authentication Vulnerability

CVSS

7.5

High

EPSS

78.1%

p100

KEV

YES

Apr 20, 2026

Exploit Today

0-100

Published: Apr 20, 2023 · Last modified: Oct 1, 2026 · CWE-287

EPSS · 30d

78.1%EPSS · 30 days78.1%

2026-09-162026-10-14

KEV catalog record

Product

PaperCut / NG/MF

Vulnerability

PaperCut NG/MF Improper Authentication Vulnerability

Added to KEV

Apr 20, 2026

Remediate by

May 4, 2026

Known ransomware use

Yes

Summary description

PaperCut NG/MF contains an improper authentication vulnerability that could allow remote attackers to bypass authentication on affected installations via the SecurityRequestFilter class.

Required action

Apply mitigations per vendor instructions, follow applicable BOD 22-01 guidance for cloud services, or discontinue use of the product if mitigations are unavailable.

Notes

https://www.papercut.com/kb/Main/PO-1216-and-PO-1219 ; https://nvd.nist.gov/vuln/detail/CVE-2023-27351

Technical description

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 SecurityRequestFilter class. The issue results from improper implementation of the authentication algorithm. An attacker can leverage this vulnerability to bypass authentication on the system. Was ZDI-CAN-19226.

Official references

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