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CVE-2023-27351: PaperCut NG/MF Improper Authentication Vulnerability

criticalknown exploitedpublic exploitCVE-2023-27351
Actively exploited. At least one CVE in this advisory is listed in the CISA Known Exploited Vulnerabilities catalog — exploitation has been observed in the wild. Treat remediation as urgent.
PaperCut NG/MF contains an improper authentication vulnerability that could allow remote attackers to bypass authentication on affected installations via the SecurityRequestFilter class.

CSIRTS triage

vendor: PaperCutproduct: NG/MFAuthentication bypass
What
An improper authentication vulnerability could allow remote attackers to bypass authentication on affected installations.
Who is affected
Deployments of PaperCut NG/MF.
Urgency
Remediation is urgent as the vulnerability is critical and has been exploited.
Action
Apply the latest security updates from PaperCut.

AI-assisted analysis generated from the source advisory — verify against the original.

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Details

Source
CISA Known Exploited Vulnerabilities (US · database · site)
Severity
critical
Published
2026-04-20
Exploitation
Observed in the wild (CISA KEV)

Original advisory: https://nvd.nist.gov/vuln/detail/CVE-2023-27351

Exploitation outlook

EPSS (FIRST.org) estimates each CVE’s probability of exploitation in the next 30 days — here is the CSIRTS.com read on those numbers.

Referenced CVEs

CVECSIRTS overviewExternal
CVE-2023-27351coverage & exploitation statusNVD · CVE.org

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