PaperCut NG/MF Improper Authentication Vulnerability
PaperCut — 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 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.
8.2
77.4%
Vector breakdown
- Attack vector
- Network
- Attack complexity
- Low
- Privileges required
- None
- User interaction
- None
- Scope
- Unchanged
- Confidentiality
- High
- Integrity
- Low
- Availability
- None
CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:L/A:N
- Published
- Apr 20, 2023
- Modified
- Apr 21, 2026
- Added to KEV
- Apr 20, 2026
- Federal patch due
- May 4, 2026
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.
Weakness classification
Proof-of-concept & exploitation references
Weaponization
Public repositories whose name or description references CVE-2023-27351, found via a live GitHub search at request time. These are community-sourced signals, not a verified working exploit - cross-check each one before relying on it, and treat higher star counts and recent activity as (weak) corroboration, not proof.
No public GitHub repositories referencing CVE-2023-27351 were found at last check. Absence here is not proof no exploit exists - see the references below for vendor advisories and write-ups.
References
Frequently asked questions
What is CVE-2023-27351?
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.
How severe is CVE-2023-27351?
CVE-2023-27351 has a CVSS base score of 8.2 out of 10 (CVSS 3.0).
Is CVE-2023-27351 actively exploited in the wild?
Yes. CVE-2023-27351 is listed in the CISA Known Exploited Vulnerabilities (KEV) catalog, added Apr 20, 2026, meaning CISA has confirmed evidence of active exploitation. It is also flagged as used in ransomware campaigns.
What is the EPSS score for CVE-2023-27351?
77.4% - meaning FIRST.org's EPSS model estimates a 77.4% probability this vulnerability will be exploited in the wild within 30 days (100% percentile among all scored CVEs).
Is there exploit tooling available for CVE-2023-27351?
Yes - a public Nuclei template referencing CVE-2023-27351 exist in public repositories we checked.
What type of vulnerability is CVE-2023-27351?
CVE-2023-27351 is classified under CWE-287 (CWE-287: Improper Authentication).
Cross-checked against
Impactr finds and proves whether CVE-2023-27351 - or flaws like it - are actually reachable in your own web apps and APIs, with a reproducible exploit as evidence.
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