CISA KEV · Known exploitedHigh

CVE-2023-27351

PaperCut NG/MF

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.

CVSS: 7.5
EPSS: 77.4%
CISA KEV: Listed
Published: 2023.04.21

PRIORITY ASSESSMENT

Immediate review

CISA has listed this vulnerability in the Known Exploited Vulnerabilities catalog.

Known exploitationConfirmed by CISA KEV

Exploit probability77.4%

Technical severityCVSS 7.5

Vulnerability overview

Affected product and versions

Product: PaperCut NG/MF
Affected versions: 22.0.5 (Build 63914), >= 15.0 < 20.1.7, >= 21.0.0 < 21.2.11, >= 22.0.0 < 22.0.9
Fixed versions: 20.1.7, 21.2.11, 22.0.9

Recommended response sequence

Confirm exposure before applying a vendor-supported change.

Full remediation guide

CISA 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.

Due date: 2026.05.04

1
Identify
Confirm that PaperCut NG/MF and an affected version are present.
2
Prioritize
Combine exploitation signals with asset exposure and business criticality.
3
Remediate
Follow the vendor advisory or supported update path and preserve rollback options.
4
Verify
Recheck the version, service health, access paths, and relevant logs.

Technical data

CVSS vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N
CWE: CWE-287
KEV added: 2026.04.20
Ransomware use: 확인됨