CVEs / CVE-2023-27351
CVE-2023-27351: PaperCut NG/MF Improper Authentication Vulnerability
- Known exploited in the CISA KEV catalog since 20 Apr 2026
- high 7.5 CVSS 3.1 (NVD)
- EPSS 78% chance of exploitation in the next 30 days, higher than 99% of CVEs (30 Oct 2026)
- Last changed at its sources
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Summary
PaperCut NG/MF contains an improper authentication vulnerability that could allow remote attackers to bypass authentication on affected installations via the SecurityRequestFilter class.
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.
Affected and fixed versions
| Product | Affected | Fixed in |
|---|---|---|
| PaperCut NG | 22.0.5 (Build 63914) | — |
Exploitation
| In CISA KEV since | 20 Apr 2026 |
|---|---|
| Due date for US federal agencies | 4 May 2026 |
| Used in ransomware campaigns | Known |
| 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. |
Severity
| CVSS 3.1 | 7.5 highCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:NScored by NVD |
|---|---|
| Weakness | CWE-287 |
References
- CVE-2023-27351 on NVD
- CVE-2023-27351 in the CISA KEV catalog
- https://www.papercut.com/kb/Main/PO-1216-and-PO-1219 (cited by CISA)
- https://www.papercut.com/kb/Main/PO-1216-and-PO-1219 Vendor Advisory
- https://www.zerodayinitiative.com/advisories/ZDI-23-232/ Third Party Advisory, VDB Entry
- https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2023-27351 US Government Resource
Sources
Exploitation status from the CISA Known Exploited Vulnerabilities catalog. EPSS scores from FIRST. Descriptions, severity and references from the National Vulnerability Database. Open-source package versions from OSV (CC-BY 4.0). Text is shown as each source states it; Stackurity does not edit it. Check the vendor's advisory before acting.
This product uses data from the NVD API but is not endorsed or certified by the NVD.