CVE-2026-81578 HIGH

CVE-2026-81578: PaperCut MF/NG: Authentication Bypass

Vendor Papercut
Product PaperCut MF/NG
Weakness CWE-305
KEV Status Known Exploited
Published August 28, 2026
Last update August 29, 2026
View on NVD All CVEs

CVSS base score

8.8/10
Attack vector Network
Attack complexity Low
Privileges required None
User interaction None
Confidentiality —
Integrity —

CVSS vector

CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:L/VI:H/VA:L/SC:N/SI:N/SA:N

What the vulnerability does

01Description

An improper access control vulnerability exists in the web management interface of PaperCut MF and PaperCut NG. Under specific conditions, unauthenticated remote requests targeting administrative functions can trigger backend actions prior to the completion of access validation checks. This allows an unauthenticated remote attacker to modify certain system configurations.

CISA mandated remediation

02CISA Required Action

Apply mitigations in accordance with vendor instructions, ensuring compliance with CISA’s BOD 26-04 Prioritizing Security Updates Based on Risk (see URL in Notes) guidance and CISA’s “Forensics Triage Requirements” (see URL in Notes). Follow applicable BOD 26-04 guidance for cloud services or discontinue use of the product if mitigations are unavailable. Stakeholders are responsible for evaluating each asset's internet exposure and ensuring adherence to BOD 26-04 patching guidelines.

Key dates

03Disclosure timeline

August 28, 2026 CVE published
August 29, 2026 Record updated

External resources

04References

NVD — National Vulnerability Database https://nvd.nist.gov/vuln/detail/CVE-2026-81578 CWE — Common Weakness Enumeration https://cwe.mitre.org/data/definitions/305.html AskarLabs — CWE-305 write-up Authentication Bypass by Primary Weakness CISA KEV Reference https://www.papercut.com/kb/Main/security-bulletin-27-aug-2026… CISA KEV Reference https://www.cisa.gov/news-events/directives/bod-26-04-prioriti… CISA KEV Reference https://www.cisa.gov/news-events/directives/bod-26-04-implemen… CISA KEV Reference https://nvd.nist.gov/vuln/detail/CVE-2026-81578