What it is
CVE-2023-27351 is an unauthenticated vulnerability affecting PaperCut NG. This vulnerability allows remote attackers to bypass authentication on affected installations of PaperCut NG 22.0.5 (Build 63914)....
Vulnerability report
Exploited in the wild
Confirmed confidence
In CISA KEV
CVE-2023-27351
NG
PaperCut / NG · 22.0.5 (Build 63914)
- Severity
- CVSS 7.5 · High
- Confidence
- Confirmed
- Exploit status
- Exploited in the wild
- EPSS
- 77.4%
- First observed
- —
- Last observed
- —
Decision summary
What security teams need to know first
Direct answers before the deeper technical record.
Is it exploited?
Yes. KEV Intelligence tracks this CVE as a known exploited vulnerability. Confidence is confirmed.
Who is affected?
PaperCut / NG 22.0.5 (build 63914).
What should we do?
Prioritize remediation. Validate affected assets and apply vendor fixes on an accelerated timeline.
Overview
NG
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.
Vendor
Product
Affected
Status
PaperCut
NG
22.0.5 (Build 63914)
Affected
- Published
- 20 Apr 2023
- Exploitation Reported
- 01 Jun 2026
- Attack vector
- Remote
- Complexity
- Low
- Privileges
- None
- User interaction
- None
Tags
nuclei_scanner
cisa
malware
CVE References
- CVE Record CVE.org · CVE Record https://www.cve.org/CVERecord?id=CVE-2023-27351
- 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/
Exploitation evidence
Why KEV Intelligence marks this CVE as exploited
Third-party attestation and first-party sensor observation are shown separately so teams can judge the evidence chain.
Exploited in the wild
CVE
Independent exploitation attestation added to the KEV Intelligence record.
Used in malware
CVE
Malware families have been linked to exploitation of this CVE.
Proof of concept available
Nuclei Templates
Public scanner or PoC coverage increases practical exploitability.
Known exploited vulnerability sources
Per-source evidence links for KEV attestations are available through the KEV Intelligence Pro API.
Learn about Pro API access| 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 |
Detection
Operational artifacts and observed signals
Make the evidence actionable in scanner, SOC, and edge-control workflows.
Observed signals
- Request targets
- 0
- User-Agents
- 0
Raw values available in Pro and Enterprise.
Scanner coverage
Nuclei template detected 01 Jun 2026.
View Nuclei template (opens in new tab)Virtual patch status
No KEV Intelligence virtual patch is currently available. Future rules ship for ModSecurity, Cloudflare, and AWS WAF.
Learn about virtual patches →Scanner Artifacts
Scanner and exploit-framework references linked to this CVE.
| Scanner | Reference | Detected |
|---|---|---|
| Nuclei | https://github.com/projectdiscovery/nuclei-templates/blob/main/http/cves/2023/CVE-2023-27351.yaml | 01 Jun 2026 |
Risk and context
Severity, weaknesses, and research context
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
EPSS
77.4%
Weaknesses
All 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
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
From disclosure to observed exploitation
-
Public PoC available
Public proof-of-concept code published
-
KEV confirmed by The Shadowserver
Exploitation attested by an external source
-
First public exploitation report
Exploit observed in malware
-
Added to CISA KEV
Listed in the CISA Known Exploited Vulnerabilities catalog
-
Nuclei template available
Scanner coverage available
-
Added to KEV Intelligence KEV Feed
High-confidence, third-party attested exploitation
-
CVE published
Vulnerability disclosed publicly
-
CVE ID reserved
Identifier reserved by the CNA
Pro API
Automate this intelligence
Confidence, exploit status, sensor telemetry, PoCs, scanner integrations, mentions, and tags are available programmatically for VM, SOC, and CTI workflows.
- Evidence confidence and provenance
- First-party sensor telemetry
- PoC and scanner references
- Affected versions and enrichment
- Automation-ready JSON delivery
GET /api/v2/pro/kevs/CVE-2023-27351
Free JSON includes basic KEV fields{
"cve_id": "CVE-2023-27351",
"confidence": "Confirmed",
"cvss_score": 7.5,
"cvss_estimated": false,
"epss_score": 0.77388,
"exploit_status": {
"exploited_in_the_wild": true,
"active_exploitation_observed": false
},
"sensor_telemetry": { "attempts": 0, "sensors": 0 }
}Early warning alerts
Get alerts on high-impact exploitation
Receive curator-selected alerts when exploitation activity warrants attention. Each alert includes the evidence and context needed to decide what requires attention now.