CVE-2023-27351
HighExploitedPublic exploitThis vulnerability allows remote attackers to bypass authentication on affected installations of PaperCut NG 22.0.5 (Build 63914).
Published Apr 25, 2023 · Updated Oct 1, 2026
Key Facts
Patch immediately- CVE-2023-27351 is a high-severity vulnerability (CVSS 7.5 v3.1) affecting Papercut Mf, Papercut Ng, NG.
- It is exploited in the wild, listed in CISA KEV, Industry KEV feed, CIRCL KEV, ENISA EUVD since Apr 28, 2023 and is known to be used in ransomware campaigns. Public exploit code is available.
- EPSS estimates a 78% probability of exploitation in the next 30 days.
- Fixed versions are available, including Papercut Mf 20.1.7, Papercut Mf 21.2.11, Papercut Mf 22.0.9.
- Brandefense priority: patch immediately, because it is listed as exploited in the wild.
CVSS v3.1
7.5
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N
EPSS (30-day exploit likelihood)
78%
Higher than 99.5% of all scored CVEs
Exploited in the wild
Yes
4 catalog listings, used by ransomware
Public exploit code
Available
Proof-of-concept or weaponized module
Get the full CVE-2023-27351 brief as a PDF
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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.
Known-Exploited Catalog Listings
| Catalog | Added | Remediation due | Ransomware use |
|---|---|---|---|
| CISA KEV | Apr 20, 2026 | May 4, 2026 | Known |
| Industry KEV feed | Apr 28, 2023 | May 4, 2026 | Known |
| CIRCL KEV | Apr 18, 2026 | May 4, 2026 | Not reported |
| ENISA EUVD | Apr 20, 2026 | n/a | Not reported |
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.
Affected Products
3 affected entries in total| Product | Affected versions | Fixed in |
|---|---|---|
| Papercut MfPapercut | See advisory | 20.1.7 |
| Papercut NgPapercut | See advisory | 20.1.7 |
| NG | >= 22.0.5 (Build 63914) | n/a |
Patched Releases
Papercut Mf
20.1.7, 21.2.11, 22.0.9
Papercut Ng
20.1.7, 21.2.11, 22.0.9
Timeline
Publicly disclosed
Apr 25, 2023
Added to Industry KEV feed
Apr 28, 2023
Added to CIRCL KEV
Apr 18, 2026
Added to CISA KEV
Apr 20, 2026
Added to ENISA EUVD
Apr 20, 2026
Last updated
Oct 1, 2026
Weakness Type
- CWE-287 Improper Authentication
References
- advisoryhttps://nvd.nist.gov/vuln/detail/CVE-2023-27350
- advisoryhttps://nvd.nist.gov/vuln/detail/CVE-2023-27351
- advisoryhttps://web.nvd.nist.gov/view/vuln/detail?vulnId=CVE-2023-1129
- advisoryhttps://www.bleepingcomputer.com/news/security/exploit-released-for-papercut-flaw-abused-to-hijack-servers-patch-now/
- advisoryhttps://www.papercut.com/kb/Main/PO-1216-and-PO-1219
FAQ
Common Questions.
This vulnerability allows remote attackers to bypass authentication on affected installations of PaperCut NG 22.0.5 (Build 63914).
Affected: Papercut Mf; Papercut Ng; NG versions >= 22.0.5 (Build 63914). The full list is in the CVE brief.
It is exploited in the wild, listed in CISA KEV, Industry KEV feed, CIRCL KEV, ENISA EUVD since Apr 28, 2023 and is known to be used in ransomware campaigns.
Yes. It was added on Apr 20, 2026 with a federal remediation due date of May 4, 2026.
Public exploit code is available.
Fixed versions are available, including Papercut Mf 20.1.7, Papercut Mf 21.2.11, Papercut Mf 22.0.9.
Brandefense priority: patch immediately, because it is listed as exploited in the wild.
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