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Known exploited vulnerability

CVE-2026-81578

highCVSS 4.0 8.8In CISA KEVEPSS 85%Published · PaperCut

The short answer

CVE-2026-81578 affects PaperCut PaperCut MF/NG and is rated high (CVSS 8.8). CISA added it to the Known Exploited Vulnerabilities catalog on 2026-08-31: attackers are using it, so patch it first. The vendor has linked a patch.

What it is

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.

Weakness: CWE-305.

Severity

8.8 high

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/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X

Exploited (CISA KEV)

Yes, since Aug 31, 2026

Federal due date Sep 14, 2026

EPSS, next 30 days

85%

Higher than 100% of scored CVEs

How it can be exploited

Attack vector
Network
Attack complexity
Low
Attack requirements
None
Privileges required
None
User interaction
None
Confidentiality impact
Low
Integrity impact
High
Availability impact
Low

What CISA says to do

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…

Affected products

PaperCut MF/NG. NVD's record lists the exact affected versions.

References

Questions

Is CVE-2026-81578 being exploited?

Yes. CISA added CVE-2026-81578 to its Known Exploited Vulnerabilities catalog on 2026-08-31, with a federal remediation due date of 2026-09-14.

How do I fix CVE-2026-81578?

CISA's 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…

From NVD, CISA KEV, FIRST EPSS and OSV.dev, checked . Status on NVD: Analyzed. The description is NVD's text, quoted as published.

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