On 2026-04-20, CISA added CVE-2023-27351 (PaperCut NG/MF) to its Known Exploited Vulnerabilities (KEV) catalog [2]. The vulnerability is listed in the catalog as "PaperCut NG/MF Improper Authentication Vulnerability" [2]. CISA requires applying mitigations in accordance with vendor instructions; see the full text below for specific requirements [2].
Backfill: this event became public on Apr 20, 2026 and we added it on Nov 10, 2026. It is not a new event.
CISA Adds PaperCut NG/MF Vulnerability CVE-2023-27351 to Known Exploited Vulnerabilities Catalog
1 min read
- Disclosed
- Apr 20, 2026
- Published
- Nov 10, 2026
- Last updated
- Nov 8, 2026
- CVSS basis
- Our assessment
- 78.1%, higher than 100% of CVEs
- Exploitation and patch status
- ExploitedKEV
- Attack vector
- Vulnerability status
- Actor type
- Motivation
On this page
30-second summary
What happened
Who is affected
Industries mainly affected: Government, Cross-industry
What to do nowOur advice
CISA requires applying mitigations in accordance with vendor instructions; see the full text for specific requirements [2].
Timeline
Technical details
CISA KEV Listing
On 2026-04-20, CISA added CVE-2023-27351 to the Known Exploited Vulnerabilities () catalog for PaperCut NG/MF [2].
Original Technical Description
PaperCut NG/MF contains an improper authentication vulnerability that could allow remote attackers to bypass authentication on affected installations via the SecurityRequestFilter class. [2]
Official Requirements
Apply mitigations per vendor instructions, follow applicable BOD 22-01 guidance for cloud services, or discontinue use of the product if mitigations are unavailable. [2]
Individual Vulnerability Record
The U.S. National Vulnerability Database (NVD) provides an independent vulnerability record and description for CVE-2023-27351 [1].
References
Official / primary3
- [1]
“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 implementa”
- [2]
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