Improper Authentication in PaperCut NG/MF (CVE‑2023‑27351) Enables Remote Bypass
What It Is
PaperCut NG/MF contains an improper authentication flaw in the SecurityRequestFilter class. The defect permits a remote attacker to bypass the normal login process and gain unauthenticated access to the management interface.
Exploitability
The vulnerability is rated High by CISA and is exploitable over the network without valid credentials. No public exploit code has been released, but the attack vector is straightforward and a proof‑of‑concept can be built from the disclosed class behavior. The CVSS v3 base score is reported as 7.8 (Remote Code Execution vector not required).
Affected Products
- Vendor: PaperCut
- Products: PaperCut NG and PaperCut MF (all supported versions prior to the vendor‑issued patch)
Why It Matters for Compliance & Audit Readiness
Access‑control failures directly challenge the Identify → Protect pillars of NIST CSF and the Authentication & Access Management controls in ISO 27001. Demonstrating that authentication mechanisms are continuously monitored, that any bypass is detected, and that evidence of remediation is retained is essential for a defensible audit trail. Organizations that rely on PaperCut for print‑service governance must map this finding to their vendor‑management and access‑control controls, capture remediation evidence, and update their control‑ownership registers to maintain trust‑by‑design.
Recommended Actions
- Patch Immediately – Apply the vendor‑released fix for CVE‑2023‑27351.
- Validate Post‑Patch – Conduct a targeted penetration test or use the vendor’s verification script to confirm the bypass is closed.
- Review Authentication Logs – Search for anomalous access attempts to the management console dating back to the last 90 days.
- Enforce MFA for Admin Accounts – Add an additional factor to any privileged PaperCut accounts.
- Update Asset Inventory – Tag all PaperCut NG/MF instances as “high‑risk” until patched and verified.
- Document Controls – Record the patch status, log review findings, and MFA configuration in your continuous control‑monitoring platform to support audit readiness.
Source: https://nvd.nist.gov/vuln/detail/CVE-2023-27351