Actively exploited in the wild. This CVE is on the CISA Known Exploited Vulnerabilities list — treat remediation as urgent. Federal remediation due by 12 May 2023. Known ransomware use
Papercut MfApplication · Papercut

CVE-2023-27350

CRITICAL · 9.8 CVSS v3.1 Published 2023-04-20
Fix available
A fix is available. Upgrade to 20.1.7 / 21.2.11 or later.
See remediation →
100/100
Remediation priority · Urgent
In the wild Ransomware High EPSS Public exploit Remotely reachable No privileges Zero-click

Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.

NVD · unedited
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 SetupCompleted class. The issue results from improper access control. An attacker can leverage this vulnerability to bypass authentication and execute arbitrary code in the context of SYSTEM. Was ZDI-CAN-18987.

Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.

dbcve analysis · high confidence

PaperCut NG 22.0.5 (Build 63914) contains an improper access control vulnerability in the SetupCompleted class that allows remote unauthenticated attackers to bypass authentication. This enables execution of arbitrary code with SYSTEM privileges.

MitigationApply the vendor security patch for CVE-2023-27350 to update PaperCut NG to a patched version. Until patched, restrict network exposure of PaperCut services to trusted sources only.

Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.

Affected products & versions What the vendor confirmedThe version ranges the vendor confirmed as vulnerable. If your version sits inside a range here, treat yourself as exposed until you have upgraded.

NVD · CPE data
Papercut MfApplication
Affected:>= 8.0, < 20.1.7>= 21.0.0, < 21.2.11>= 22.0.0, < 22.0.9
Papercut NgApplication
Affected:>= 8.0, < 20.1.7>= 21.0.0, < 21.2.11>= 22.0.0, < 22.0.9

CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.

From the vector
Attack vector
Network
Complexity
Low
Privileges
None
User interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.

dbcve checks

Work through these to decide whether this CVE applies to you.

  1. Identify installed PaperCut version
    Locate the PaperCut installation directory and check the version file, or access the PaperCut admin interface and navigate to Help > About to view the version number
    Affected if The installed version falls within any of these ranges: >= 8.0 and < 20.1.7, or >= 21.0.0 and < 21.2.11, or >= 22.0.0 and < 22.0.9
  2. Verify SetupCompleted endpoint accessibility
    Attempt to access the SetupCompleted endpoint via HTTP/HTTPS request to the PaperCut server (typically at a URL path containing 'SetupCompleted'), without providing any authentication credentials
    Affected if The request returns a successful response or allows access without requiring authentication, indicating the vulnerability is exploitable
  3. Inspect for unauthorized administrative accounts
    In the PaperCut admin interface, review the Users > Admin Users section, or inspect the internal database/configuration files for any unfamiliar administrative accounts or modified user privileges
    Affected if New or unexpected administrative accounts exist that were not created by legitimate administrators, suggesting exploitation
  4. Check for unexpected scheduled tasks or scripts
    On the Windows server hosting PaperCut, review the Task Scheduler for unfamiliar scheduled tasks, and examine the PaperCut server-app directory for newly created or modified executable files or scripts
    Affected if Unexpected scheduled tasks, scripts, or executables are present that align with the timeframe of potential exploitation

You are affected if your installed PaperCut NG/MF version is within the affected ranges AND the SetupCompleted endpoint can be accessed without authentication, or if unauthorized administrative activity is detected on the server.

Generated from the published advisory. Verify against your own configuration.

Check your environment

Paste your version and any relevant configuration and it will be compared against the affected criteria above. Do not include secrets or credentials.

AI-assisted, checked against the advisory. Informational, not a guarantee.

Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.

dbcve · scoped
Upgrade available Upgrade to 20.1.7 / 21.2.11 / 22.0.9 or later
Fixed in 20.1.721.2.1122.0.9
Interim mitigation

Apply the vendor security patch for CVE-2023-27350 to update PaperCut NG to a patched version. Until patched, restrict network exposure of PaperCut services to trusted sources only.

Recommended fix High confidence

PaperCut MF/NG 22.0.9 (or later) - the minimum fixed version for each affected branch is 20.1.7, 21.2.11, or 22.0.9

  1. 1. Identify the current PaperCut MF or NG version installed by checking the server or admin interface
  2. 2. Download the appropriate fixed version from the official PaperCut website: 20.1.7, 21.2.11, or 22.0.9 (or later)
  3. 3. Backup the PaperCut installation directory and database before upgrading
  4. 4. Stop the PaperCut service to ensure a clean upgrade process
  5. 5. Run the installer for the chosen fixed version
  6. 6. Follow the installation wizard prompts to complete the upgrade
  7. 7. Restart the PaperCut service after installation completes
  8. 8. Verify the upgrade was successful by logging into the admin interface and checking the build version
Caveat Standard upgrade; review release notes for any configuration or feature changes between versions

Generated from the published advisory — verify against the referenced sources before acting.

Fix this in Papercut Mf Exploited in the wild — priority engagement
  • Consultation4.0 h
  • Implementation4.0 h
  • Testing8.0 h
  • Review / QA4.0 h
20.0 hours of engineering $3,440
Get it fixed fast

An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $5,504.

Scan for this in your stack

Free · runs locally
dbcve dependency scanner

Check whether your project pulls in CVE-2023-27350 — or any other known-vulnerable package — straight from your lock files. Free and open source; it runs locally and uploads nothing.

References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2023-27350 in production — separate from our analysis above.

No notes yet

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What this is

A place for practitioners to share what actually worked: a mitigation you’ve tested, a configuration change, a version- or environment-specific caveat, or a link to a verified patch. The most useful notes rise to the top as peers upvote them, so the signal stays high.

What belongs here
  • Verified mitigations, workarounds, and config changes
  • Version or environment caveats, and links to real fixes
  • No weaponised exploit code, or anything meant to cause harm
  • No spam, self-promotion, credentials, or personal data