Security Resilience

CVE-2023-27350

Papercut Mf 8.0 – 20.1.7

CISA KEVActive ExploitationEUVD ExploitedPublic PoCRansomware-linked
Published
20 April 2023
Modified
27 October 2025
KEV Added
21 April 2023
Patch / advisory
CVSS Score v3.1 9.8
Click a component to see what it means
Raw vectorCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
EPSS Score 0.99 100.0th percentile
Risk Priority 97 floored blend · peak EPSS

CVSS and EPSS are reproduced from their sources (NVD, FIRST EPSS). Risk Priority is our own derived reading, not an NVD score.

Summary

CVE-2023-27350 is a critical-severity Improper Access Control (CWE-284) vulnerability in Papercut Papercut Mf. Its CVSS base score is 9.8 (Critical).

Operationally, ranked in the top 0.0% of CVEs by exploit likelihood; CISA has added it to the Known Exploited Vulnerabilities catalog; a public proof-of-concept is referenced.

Deeper analysis AI-assisted summary

Synthesised by an AI model from the NVD description and linked references — a reading aid, not an authoritative source.

CVE-2023-27350 is an authentication bypass vulnerability in PaperCut NG version 22.0.5 (Build 63914) that stems from improper access control in the SetupCompleted class. The flaw permits remote attackers to reach administrative functionality without supplying credentials, ultimately allowing code execution with SYSTEM privileges on the underlying host. It carries a CVSS 3.1 base score of 9.8 and was originally reported as ZDI-CAN-18987.

Unauthenticated attackers on the network can directly exploit the issue to bypass login checks and run arbitrary commands in the SYSTEM context. Public exploit code targeting this vector has been published, confirming that no prior authentication or user interaction is required for successful compromise.

References list multiple PacketStorm entries containing proof-of-concept scripts for authentication bypass and remote code execution against PaperCut NG/MF 22.0.4 and later builds, along with a Sophos advisory documenting observed increases in active exploitation attempts shortly after disclosure.

The associated EPSS score currently stands at 0.9426 with a recorded peak of 0.9724, reflecting sustained and widespread exploitation interest.

OWASP Top 10 for Web (2025)

EU & UK References

Vulnerability Data

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.…

more

An attacker can leverage this vulnerability to bypass authentication and execute arbitrary code in the context of SYSTEM. Was ZDI-CAN-18987.

CWE(s)
KEV Date Added
21 April 2023

Related Threats

Threat-Actor AttributionAI

Cl0p
Cl0p ransomware exploited PaperCut NG zero-day CVE-2023-27350 (CISA KEV + Sophos 2023 reporting).
AnonOps
Malicious Actors Exploit CVE-2023-27350 in PaperCut MF and NG | CISA
Apple Inc. (Masimo pulse-oximetry trade-secret 2020-2024)
Understanding Ransomware Threat Actors: LockBit | CISA
Microsoft Corp. (Salesforce / Slack engineer recruitment claims)
Understanding Ransomware Threat Actors: LockBit | CISA
LockBit
Understanding Ransomware Threat Actors: LockBit | CISA
Clop
2023 Top Routinely Exploited Vulnerabilities | CISA

CVEs Like This One

CVE-2025-24989Shared CWE-284both on KEV
CVE-2012-4681Shared CWE-284both on KEV
CVE-2013-0422Shared CWE-284both on KEV
CVE-2012-1723Shared CWE-284both on KEV
CVE-2025-33073Shared CWE-284both on KEV
CVE-2023-29298Shared CWE-284both on KEV
CVE-2023-38205Shared CWE-284both on KEV
CVE-2026-34908Shared CWE-284both on KEV
CVE-2011-3544Shared CWE-284both on KEV
CVE-2021-22941Shared CWE-284both on KEV

Affected Assets

papercut
papercut mf
8.0 — 20.1.7 · 21.0.0 — 21.2.11 · 22.0.0 — 22.0.9
papercut
papercut ng
8.0 — 20.1.7 · 21.0.0 — 21.2.11 · 22.0.0 — 22.0.9

Mitigating Controls

Likely Mitigating Controls AI

Per-CVE control mapping for this CVE has not run yet; the list below is derived from the weakness types (CWEs) cited in the NVD entry.

addresses: CWE-284

The access control policy and procedures directly mandate and enforce proper access control mechanisms across the organization.

addresses: CWE-284

Device lock enforces restricted access until re-authentication, directly reducing unauthorized use of active sessions.

addresses: CWE-284

Supervision and review of access control activities directly detects and remediates improper access configurations or usages.

addresses: CWE-284

Explicitly identifying and documenting actions permitted without identification or authentication enforces proper access control boundaries by defining justified exceptions.

addresses: CWE-284

By automatically labeling outputs with security attributes, the control supports attribute-based enforcement and reduces exploitability of improper access control weaknesses.

addresses: CWE-284

Associating and retaining security attributes with data directly supports enforcement of access control decisions across storage, processing, and transmission.

addresses: CWE-284

Requiring prior authorization for each remote access type prevents improper access control over remote connections.

addresses: CWE-284

Requiring authorization of wireless access before allowing connections enforces proper access control for this access method.

Mitigating Controls (ISO/IEC 27001:2022 Annex A) AI

Derived directly from the weakness types (CWEs) cited in the NVD entry via our AI-authored CWE→ISO cross-walk (authority under review) — links open the control.

blocks

A.5.1 only requires that an information security policy and topic-specific policies (including on access control) exist and are reviewed; it does not itself enforce, implement or act on any access restriction, so the weakness can still be exploited (per the owner's explicit rule that governance/dependency clauses score none on effect verbs).

blocks

A.5.15 directly mandates determining requirements, defining/implementing topic-specific access control policy+rules (with explicit references to 8.3, 5.16, 5.18), and enforcing authorized access while preventing unauthorized access, which squarely stops exploitation of most CWE-284 instances; the bounded remainder is the physical slice (explicitly delegated to 7.2-7.4) plus any second-order defects like path traversal that are not authorization decisions.

blocks

A.5.16's identity lifecycle (unique binding, timely disable/remove, no duplicates, oversight of shared/non-human) directly stops most improper access by ensuring the actor in an access decision is correctly identified and authorized; the bounded remainder is non-identity mechanisms in CWE-284 such as path traversal or CSRF that do not turn on actor identity at all.

blocks

A.5.18 directly governs the provisioning, review, adjustment and timely revocation of both physical and logical access rights per business rules, segregation of duties and risk-evaluated changes/terminations; this stops most unauthorized-actor exploitation paths named by CWE-284, with a bounded remainder (e.g. path-traversal or CSRF cases that are not authorization decisions at all)

blocks

A.5.2 defines and assigns roles/responsibilities for protection of information and risk acceptance; it does not itself enforce any access decision and cannot stop exploitation of improper access control (per the owner's labeling rule: governance/dependency clauses do not score on prevent/mitigate verbs)

finds

Ongoing audits and performance reviews of suppliers detect and correct situations where access controls or privilege assignments are weaker than contractually required, limiting an attacker's ability to exploit improper access control in the supplier's environment.

Hardening callouts derived

DISA STIG baselines are authored against specific weaknesses. Where this CVE cites a broad weakness class, the mapping is not asserted at that abstraction (owner ruling, 2026-09-25: grade only at Base and below), so no rule is shown here rather than a rule shown against the wrong grain.

  • No fine-grained STIG row for CWE-284, a pillar-level weakness. Rules are authored against its narrower children: CWE-749, CWE-1220.

References