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Weekly Signal
Live intelligence Updated 20 Aug 2026 · 12:21 UTC

Papercut · NG/MF, Papercut Mf, Papercut Ng

CVE-2023-27351

PaperCut NG/MF Improper Authentication Vulnerability

Recommended action

Validate affected assets and exposure now, then remediate on an accelerated schedule. Apply mitigations per vendor instructions, follow applicable BOD 22-01 guidance for cloud services, or discontinue use of the product if mitigations are unavailable.

View response plan
CVSS7.5
EPSS77.4%
KEVYes
ExploitationConfirmed exploitation
RemediationExplicit patch identified ↓

Assessment

Why it matters

CISA lists this vulnerability as known to be exploited; exploitation is confirmed; EPSS is 77.4%; technical severity is CVSS 7.5.

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.

Who should care

  • Teams operating NG/MF, Papercut Mf, Papercut Ng
  • Vulnerability and exposure management teams
  • Security operations teams monitoring exploitation activity

Response plan

What I would do

  1. Confirm whether NG/MF, Papercut Mf, Papercut Ng is present in the environment.
  2. Identify affected versions and establish whether vulnerable services are exposed or reachable.
  3. Apply mitigations per vendor instructions, follow applicable BOD 22-01 guidance for cloud services, or discontinue use of the product if mitigations are unavailable.
  4. Review relevant security telemetry for evidence of attempted or successful exploitation.
  5. Document the remediation decision and track it to verified completion.

Treatment intelligence

Remediation intelligence

Not yet verified

Vendor sources are listed before government and third-party guidance. Confirm product applicability and change prerequisites before deployment.

Verification noteAutomated link verification has not completed for this guidance yet.

Patch

Required Action

Technical details

CVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N
CWE
CWE-287
Affected versions
Papercut NG/MF; Papercut Papercut Mf (Start Including 15.0, End Excluding 20.1.7 | Start Including 21.0.0, End Excluding 21.2.11 | Start Including 22.0.0, End Excluding 22.0.9); Papercut Papercut Ng (Start Including 15.0, End Excluding 20.1.7 | Start Including 21.0.0, End Excluding 21.2.11 | Start Including 22.0.0, End Excluding 22.0.9)
Fixed versions
Papercut Papercut Mf (Fixed from 20.1.7, 21.2.11, 22.0.9); Papercut Papercut Ng (Fixed from 20.1.7, 21.2.11, 22.0.9)
Published
20 April 2023
Attack vector
Network
Privileges required
None
User interaction
None

Signal timeline

  1. CVE published
  2. Added to CISA KEV
  3. Latest EPSS score: 77.4%
  4. Signal calculated at 83

External references

Live public intelligence This assessment combines public-source evidence. Validate the affected product, version and exposure against your own environment before making a risk decision.