CVE-2023-27351

Confirmed PUBLISHED

This vulnerability allows remote attackers to bypass authentication on affected installations of PaperCut NG 22.0.5 (Build 63914). Authentication...

PaperCut · NG

1 day faster than CISA KEV

Exploited in the wild Used in malware PoC available

Recommended Action

Prioritize remediation. Validate affected assets and apply vendor fixes on an accelerated timeline.

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Confidence

Confirmed

Exploitation Status

Exploited in the wild

Observed in Sensors

Attempts (30d)

—

Unique Attacker IPs

—

CISA KEV

In CISA KEV

CVSS / EPSS

7.5 High EPSS 78.4%

At a Glance

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.

nuclei_scanner cisa malware

CVE Published: Apr 20, 2023
Exploitation Reported: Jun 01, 2026
CVSS: 7.5 High
EPSS: 78.4%

Remote Low complexity No user interaction Unauthenticated

Affected Versions

Vendor	Product	Version	Status
PaperCut	NG	22.0.5 (Build 63914)	Affected

CVE References

papercut.com/kb/Main/PO-1216-and-PO-1219 papercut.com · CVE Record https://www.papercut.com/kb/Main/PO-1216-and-PO-1219
zerodayinitiative.com/advisories/ZDI-23-232 zerodayinitiative.com · CVE Record https://www.zerodayinitiative.com/advisories/ZDI-23-232/

Recommended Actions

Prioritize remediation. Validate affected assets and apply vendor fixes on an accelerated timeline.
Check enrichment artifacts for scanner coverage and available PoCs before rolling remediation validation.
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Known Exploited Vulnerability Sources

Catalogues that list this CVE as a known exploited vulnerability.

Per-source evidence links for KEV attestations are available through the KEVIntel Pro API.

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Source	Added
CVE First	2026-06-01 13:22 UTC
CISA	2026-06-02 14:01 UTC
The Shadowserver	2026-06-04 00:00 UTC

Scanner Artifacts

Nuclei and Metasploit references linked to this CVE.

Scanner	Reference	Detected
Nuclei	https://github.com/projectdiscovery/nuclei-templates/blob/main/http/cves/2023/CVE-2023-27351.yaml	Jun 01, 2026

CVSS Scores

CVSS v3.1 7.5 High

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

CVSS v3.0 8.2 High

CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:L/A:N

Exploitation Status

Exploited in the wild

Recorded 2026-06-01 13:22:22 UTC · CVE

Used in malware

Recorded 2026-06-02 14:01:39 UTC · CVE

Proof of concept available

Recorded 2026-06-12 14:20:59 UTC · Nuclei Templates

Weaknesses (CWE)

CWE-287

Improper Authentication

Scanner Integrations

Scanner	Reference	Detected
Nuclei	https://github.com/projectdiscovery/nuclei-templates/blob/main/http/cves/2023/CVE-2023-27351.yaml	Jun 01, 2026

Potential Proof of Concepts

These PoCs are unverified and could contain malware. Use at your own risk.

PaperCut NG - Authentication Bypass

nuclei · Created Unknown

Timeline

Key exploitation, disclosure, scanner coverage, and KEV attestation events for this CVE.

12 Jun 2026 14:20 UTC about 1 month ago

12 Jun 2026 14:20 UTC · about 1 month ago

Public PoC available

Public proof-of-concept code published
4 Jun 2026 00:00 UTC about 2 months ago

4 Jun 2026 00:00 UTC · about 2 months ago

KEV confirmed by The Shadowserver

Exploitation attested by an external source
2 Jun 2026 14:01 UTC about 2 months ago

2 Jun 2026 14:01 UTC · about 2 months ago

First public exploitation report

Exploit observed in malware
2 Jun 2026 14:01 UTC about 2 months ago

2 Jun 2026 14:01 UTC · about 2 months ago

Added to CISA KEV

Listed in the CISA Known Exploited Vulnerabilities catalog
1 Jun 2026 15:34 UTC about 2 months ago

1 Jun 2026 15:34 UTC · about 2 months ago

Nuclei template available

Scanner coverage available
1 Jun 2026 13:22 UTC about 2 months ago

1 Jun 2026 13:22 UTC · about 2 months ago

Added to KEVIntel KEV Feed

High-confidence, third-party attested exploitation
20 Apr 2023 00:00 UTC over 3 years ago

20 Apr 2023 00:00 UTC · over 3 years ago

CVE published

Vulnerability disclosed publicly
28 Feb 2023 00:00 UTC over 3 years ago

28 Feb 2023 00:00 UTC · over 3 years ago

CVE ID reserved

Identifier reserved by the CNA

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Confidence scoring, exploit status, sensor telemetry, PoCs, scanner integrations, mentions, and tags are available programmatically for VM, SOC, and CTI workflows.

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Pro API Example

GET /api/v2/pro/kevs/CVE-2023-27351

{
  "cve_id": "CVE-2023-27351",
  "title": "This vulnerability allows remote attackers to bypass authentication on affect...",
  "affected_vendor": "PaperCut",
  "affected_product": "NG",
  "affected_versions": [
    { "vendor": "...", "product": "...", "status": "affected", "display_label": "..." }
  ],
  "confidence": "Confirmed",
  "cvss_score": 7.5,
  "epss_score": 0.7842,
  "exploit_status": {
    "exploited_in_the_wild": true,
    "active_exploitation_observed": false
  },
  "sensor_telemetry": { "...": "Pro API fields" },
  "proof_of_concepts": [ "..." ],
  "scanner_integrations": [ "..." ]
}

The free JSON API returns basic KEV fields only. Confidence, telemetry, and artifact enrichment require Pro API access.

CVE-2023-27351

At a Glance

Affected Versions

CVE References

Recommended Actions

Known Exploited Vulnerability Sources

Scanner Artifacts

Virtual Patch

CVSS Scores

Exploitation Status

Weaknesses (CWE)

Scanner Integrations

Potential Proof of Concepts

Timeline

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