CVE-2023-27351
Actively exploited. CVE-2023-27351 is listed in the CISA Known Exploited Vulnerabilities catalog (added 2026-04-20) — exploitation has been observed in the wild, and US federal agencies are required to remediate it under BOD 22-01. Treat patching as urgent.
Public exploit code is available. Proof-of-concept or working exploit code for CVE-2023-27351 is indexed in Nuclei. Expect opportunistic scanning and exploitation attempts — prioritize remediation.
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
- 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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Exploitation outlook
- Exploitation confirmedAlready exploited in the wild (CISA KEV) — the prediction phase is over. Patch now. Riskier than 100% of all EPSS-scored CVEs.
Exploit availability
Public exploit or proof-of-concept code for CVE-2023-27351 is indexed in these free datasets. Available exploit code raises real-world risk independent of the CVSS score.
- NucleiA nuclei-templates detection/PoC template exists for this CVE.look it up ↗
Advisory coverage (1)
- criticalexploitedCVE-2023-27351: PaperCut NG/MF Improper Authentication Vulnerabilitycisa-kev · 2026-04-20
External references
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[](https://www.csirts.com/cve/CVE-2023-27351)