CVE entry · CVE-2023-27351
CVE-2023-27351: PaperCut NG/MF Improper Authentication Vulnerability
PaperCut NG/MF contains an improper authentication vulnerability that could allow remote attackers to bypass authentication on affected installations via the SecurityRequestFilter class.
- Actively exploited: added to CISA’s KEV catalog on April 20, 2026.
- Used by ransomware, according to CISA.
- Remediation deadline for US federal agencies: May 4, 2026.
Description from CISA’s KEV catalog.
What to do
- Check whether your estate includes PaperCut NG/MF, including internet-facing devices.
- Apply the vendor’s patch or mitigations (references below). Failing that, isolate the product or stop using it, as CISA requires of US federal agencies.
- An exploited vulnerability has often been used before it was fixed: look for signs of compromise, especially on internet-facing devices.
References
- Vendor advisory or reference cited by CISA (www.papercut.com)
- NVD entry (NIST)
- CISA KEV catalog