CVE-2023-27351: PaperCut NG/MF authentication bypass in SecurityRequestFilter

CVE-2023-27351 · Severity: critical · CVSS 8.2 · Exploited in the wild · Published 2026-04-20

PaperCut NG and MF are print management solutions used by organizations to manage and secure printing. A critical security flaw allows unauthorized individuals to bypass login requirements and gain administrative access to the system over the network. This could lead to the exposure of sensitive print data or unauthorized changes to system configurations.

Technologies: PaperCut Mf, PaperCut Ng. Vendors: PaperCut.

Quick answers

Is CVE-2023-27351 exploited in the wild?
Yes. CVE-2023-27351 is known to be exploited in the wild, first recorded on 20 April 2026. Treat it as urgent.
How severe is CVE-2023-27351?
Critical severity, with a CVSS score of 8.2, published 20 April 2026.
Which products and versions are affected?
PaperCut Mf 15.0.0 to 20.1.6, 21.0.0 to 21.2.10, 22.0.0 to 22.0.8; PaperCut Ng 15.0.0 to 20.1.6, 21.0.0 to 21.2.10, 22.0.0 to 22.0.8.
Is there a fix for CVE-2023-27351?
No fixed version is recorded yet. Check the vendor's advisory in the references below. If you run it, Junglewise drafts a mitigation that fits your setup and applies it once you approve, with senior security engineers behind it.
How is CVE-2023-27351 attacked?
It is attacked over the network, in a network appliance.
Am I affected by CVE-2023-27351?
Check whether you run PaperCut Mf or PaperCut Ng at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

Technical details

This vulnerability is classified as Improper Authentication (CWE-287) within the SecurityRequestFilter class of PaperCut NG and MF. The flaw stems from an improper implementation of the authentication algorithm, which allows a remote, unauthenticated attacker to bypass security checks via specially crafted network requests. Successful exploitation grants the attacker administrative access to the application interface. This vulnerability has been observed being exploited in the wild. Patches are available in versions 20.1.7, 21.2.11, 22.0.9, and later.

Affected products

  • PaperCut PaperCut MF 15.0.0 to 20.1.6, 21.0.0 to 21.2.10, 22.0.0 to 22.0.8
  • PaperCut PaperCut NG 15.0.0 to 20.1.6, 21.0.0 to 21.2.10, 22.0.0 to 22.0.8

Timeline

  • 2023-04-20: disclosed: Initial disclosure by Zero Day Initiative
  • 2026-04-20: kev added: Added to CISA Known Exploited Vulnerabilities catalog
  • 2026-04-20: exploited: Confirmed active exploitation in the wild

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