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NVD / CVE Program· CNA zdi

CVE-2023-27351: This vulnerability allows remote attackers to bypass authentication on affected installations of PaperCut NG 22.0.5 (Build 63914).

HighCVSS 7.5 · v3.1KEVWeaponized No fix recorded

Noroxi assessment

Priority: Now (action score 83/100)

  • CISA has confirmed exploitation in the wild (Apr 20, 2026); it is known to be used in ransomware campaigns. Remediation deadline for US federal agencies: May 4, 2026.
  • A ready-made attack module is public (Nuclei); exploiting it takes no special expertise.
  • Probability of exploitation in the next 30 days: 78% (FIRST EPSS); higher than 99.5% of all records.
  • Anyone who can reach it over the internet can trigger it. No account or password is required. No user action is required. No special conditions are required; it is repeatable.
  • According to CISA the attack is automatable: targets can be found by mass scanning.
  • According to the record, no fixed version is available yet.
  • Mentioned 1 time in Turkish national cyber security advisories (siberguvenlik.gov.tr).

Patch today or shut off access. Until a fix is released, restrict access to the affected component and follow the vendor's advisory.

Generated automatically from the record's data: CVSS (NVD and CNA), CISA KEV and SSVC, FIRST EPSS, exploit sources, fixed versions. How we calculate it

Primary sources: NVD · CVE.org · CISA KEV · FIRST EPSS

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.

Published
Apr 20, 2023
Updated
Oct 1, 2026
EPSS
78.0% · 99th percentile

Report tools

JSON

Action score

83

Now

Patch today or shut off access.

CVSS
30 / 40 · 7.5 / 10
CISA KEV
30 / 30 · Listed
EPSS
23 / 30 · 78.0%

CISA SSVC decision

Exploitation
active
Automatable
yes
Technical impact
total

Vulnrichment: CISA's decision-tree inputs.

CNA vs NVD score

NVD
7.5
CNA · zdi
8.2
0.7 point gap

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

The score given by the assigning authority versus NVD’s independent score. A gap means the severity is contested.

Actively exploited in the wild

CISA added this to its Known Exploited Vulnerabilities catalog on Apr 20, 2026. That signals real attacks, not theory.

Remediation deadline for US federal agencies: May 4, 2026.

Known to be used in ransomware campaigns.

Get told when this record changes

  • In CISA KEV: exploitation in the wild confirmed
  • Weaponized exploit exists
  • No fixed version yet

If any of these changes, we'll tell you in the daily email digest.

Follow CVE-2023-27351

When you'll hear from us

  • when it enters CISA KEV
  • when exploit code appears or is weaponized
  • when the record is updated (including a fixed version)
  • when EPSS rises 20 points in a week

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Noroxi analysis

What does it mean in your environment?

The assessment above is generated automatically from the record's data; it doesn't know your environment. Our team verifies on your systems whether this vulnerability is actually exploitable and which mitigation is enough.

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Affected systems

Is your version affected?

Pick the product and type the version you run. It's compared with this record's version ranges in your browser; the version isn't sent anywhere.

VendorProduct
papercutpapercut mf
papercutpapercut ng

Versions reported by the vendor

Affected version ranges reported by the assigning authority (zdi). Independent of NVD's CPE analysis and usually ahead of it.

  • PaperCut NG

    • 22.0.5 (Build 63914)affected
Affected versions · NVD (6)

NVD version ranges (for catalog products). Add the product to your stack with a version and matching uses these.

  • papercut papercut mf15.0 and later · before 20.1.7
  • papercut papercut mf21.0.0 and later · before 21.2.11
  • papercut papercut mf22.0.0 and later · before 22.0.9
  • papercut papercut ng15.0 and later · before 20.1.7
  • papercut papercut ng21.0.0 and later · before 21.2.11
  • papercut papercut ng22.0.0 and later · before 22.0.9

Same product

papercut: all records

Other highest-scoring records for the same primary product.

  • CVE-2023-27350This vulnerability allows remote attackers to bypass authentication on affected installations of PaperCut NG 22.0.5 (Build 63914).KEV
    99Now
  • CVE-2026-81578PaperCut MF/NG: Authentication BypassKEV
    90Now
  • CVE-2026-82078PaperCut MF/NG: Unsafe Dynamic Class Loading in Database ConnectorKEV
    86Now

Published before and after this one in the same product

  • ← EarlierCVE-2019-8948Feb 20, 2019 · PaperCut MF before 18.3.6 and PaperCut NG before 18.3.6 allow script injection via the user interface, aka PC-15163.
    40Plan
  • ← EarlierCVE-2019-12135Jun 6, 2019 · An unspecified vulnerability in the application server in PaperCut MF and NG versions 18.3.8 and earlier and versions 19.0.3 and earlier…
    40Plan
  • Later →CVE-2023-2533Jun 20, 2023 · PaperCut MF/NG 22.0.10 (Build 65996 2023-03-27) - Remote code execution via CSRFKEV
    74This week

Remediation

Which version to upgrade to

Fix versions compiled from the vendor, package registries and Microsoft. Verify the vendor's note before upgrading.

No fix version is recorded for this entry. Check the references for vendor advisories.

Exploit status

Weaponized

A ready exploit tool or active in-the-wild use is known for this vulnerability. This should be your top priority.

Evidence

  • Nuclei detection template ×1

Noroxi does not host or link to exploit code. Metasploit module names and Nuclei template ids are shown (names, not code); Exploit-DB entries and PoC repositories are given as counts only.

Public exploit evidence
SourceKindDate
Nuclei detection templateNuclei template CVE-2023-27351 —

Research context

For pentesters and researchers: attack profile, score disagreement, timeline, patch commits, credits, variant and chain candidates, bug bounty scope. All derived from existing data; no exploit code.

Timeline

From publication to today: proof of concept, Metasploit module, CISA KEV and fix record. Dates are as reported by the sources.

  1. Published
  2. CISA KEV+1095 d
  3. TodayNov 13, 2026+1303 d

Credits

All researchers

Finders, reporters and analysts named in the CNA record. Click a name for that researcher’s other records.

National notice (Türkiye Cybersecurity Directorate / USOM)

Official security notices citing this record; remediation advice is on the agency's page.

All national notices →

Not on record for this CVE: EPSS history · patch commit or PR link · variant or chain candidate · public bounty program.

Technical details

Attack conditions

  • Anyone who can reach it over the internet can trigger it.
  • No account or password is required.
  • No user action is required.
  • No special conditions are required; it is repeatable.

If successful

Confidentiality
high · data can be read
Integrity
none
Availability
none
Attack vector
Network
Attack complexity
Low
Privileges required
None
User interaction
None
Scope
Unchanged
Confidentiality impact
High
Integrity impact
None
Availability impact
None

Weakness class (CWE)

CWE-287 · Improper Authentication

CVSS vector

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

nvd-primary

Root cause

Authentication is added route by route instead of being enforced in one place. When a route added later bypasses the shared middleware, the session check never runs for it.

The bug in code

The whole CWE-287 class

A representative example of this vulnerability class. Not the vendor's source code; it shows the faulty pattern and its fix.

Vulnerable

ts
app.use("/admin", requireSession, adminRouter);
// Route added later skips the middlewareapp.post("/admin-api/config", updateConfig);

Fixed

ts
const admin = express.Router();admin.use(requireSession, requireRole("admin"));
admin.post("/config", updateConfig);app.use("/admin", admin);

Attack context

MITRE CAPEC attack patterns and ATT&CK techniques for this weakness class (CWE). A starting point for detection rules and threat hunting.

References

Show all references (2 more)

Vendor advisories and official records. Exploit/PoC links are deliberately left out.

All records