CVE-2023-27350
CRITICALCVE-2023-27350 is a critical-severity (CVSS 9.8) CWE-284 vulnerability in papercut papercut mf. 20 public exploit references exist, so weaponization risk is real. O3 Security detects and blocks CVE-2023-27350 exploitation at runtime via eBPF exploit-chain detection and L7 egress monitoring, even on unpatched systems.
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.…
Exploitation Status
Actively exploited in the wild
- CISA’s SSVC triage classifies this CVE as under active exploitation.
- CISA assesses this as automatable — exploitation doesn’t require manual, per-target effort, which raises the odds of mass scanning and opportunistic attacks.
- A successful exploit gives an attacker total control of the affected component, not partial access.
Exploitation and automatability from CISA’s SSVC triage for CVE-2023-27350.
EPSS Exploitation Probability
EPSS (Exploit Prediction Scoring System) is a daily probability model maintained by FIRST.org. It estimates the likelihood a CVE will be exploited in production environments within the next 30 days, derived from real-world threat intelligence signals.
How urgent is this, really
CVE-2023-27350 plotted by exploitation likelihood (EPSS) against impact (CVSS). The shaded corner — EPSS 50%+ and CVSS 7.0+ — is where this CVE sits: patch-first territory.
Where this sits among everything scored
Of 368,770 CVEs with a current EPSS score, this one falls in the ≥ 90% band (highlighted). Real counts from FIRST.org, not a sample — log-scaled since the landscape is heavily right-skewed.
Description
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. An attacker can leverage this vulnerability to bypass authentication and execute arbitrary code in the context of SYSTEM. Was ZDI-CAN-18987.
Affected Products
papercut mfpapercutpapercut ngpapercutResearch use only. For defensive security, authorized penetration testing, and academic research only. Never execute exploit code against systems without explicit written authorization.
PaperCut NG/MG 22.0.4 - Authentication Bypass
by MaanVader · Apr 25, 2023
PaperCut NG/MG 22.0.4 - Remote Code Execution (RCE)
by MaanVader · May 23, 2023
Detection & mitigation playbook
Vendor / applianceDetect
Inventory every papercut papercut mf deployment and check each version against the affected-products list above. Because the exploit targets the running system rather than your application code, also watch for remote code execution at the network and runtime layer — O3 flags the exploit behaviour from runtime telemetry and egress traffic even before a vulnerable build is confirmed.
Fix
Apply the papercut papercut mf security patch or hotfix for CVE-2023-27350 on the affected version, following the vendor advisory for your exact build.
Workarounds
Cut exposure now: restrict the management/admin interface to trusted networks, segment the device, and apply the vendor's recommended configuration mitigations and any WAF/IPS signature. O3's runtime protection blocks the exploit chain at execution, holding the line on unpatched or end-of-life systems until you can patch.
How O3 protects you
O3 detects and blocks CVE-2023-27350 exploitation at runtime: eBPF exploit-chain detection, plus L7 egress monitoring that catches the post-exploitation callback and severs the attacker's outbound channel.
Tailored to CVE-2023-27350. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.
Frequently Asked Questions
Is CVE-2023-27350 being exploited in your environment?
O3's eBPF runtime sensors and L7 egress monitoring detect and block the CVE-2023-27350 exploit chain at execution — protecting unpatched and end-of-life systems until the vendor patch is applied.