CVE-2026-81578

Analyzed
Published: 28 Aug 2026, 11:39
Last modified:31 Aug 2026, 15:29

Vulnerability Summary

Overall Risk (default)
high
70/100
CVSS Score
9.8 CRITICAL
v3.1 (nvd)
EPSS Score
0.39% LOW
0% probability 0.00%
KEV
Listed
CISA
1 listing
Ransomware
No reports
Public exploits
1 found
Dark Web
Not detected

Timeline

28 Aug 2026, 11:39
Published
Vulnerability first disclosed
31 Aug 2026, 00:00
Added to CISA KEV
PaperCut NG/MF Missing Authentication for Critical Function Vulnerability
31 Aug 2026, 15:29
Last Modified
Vulnerability information updated
14 Sept 2026, 00:00
CISA Remediation Due
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.

Description

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.

CVSS Metrics

  • v4.0•HIGH•Score: 8.8CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:L/VI:H/VA:L/SC:N/SI:N/SA:N
  • v4.0•HIGH•Score: 8.8CVSS: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
  • v3.1•CRITICAL•Score: 9.8CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

EPSS Trends

Current EPSS score: 0.39%• Percentile: 32%

Techniques & Countermeasures

  • CWE-305•Authentication Bypass by Primary Weakness

    The authentication algorithm is sound, but the implemented mechanism can be bypassed as the result of a separate weakness that is primary to the authentication error.

Affected Systems

  • papercut•papercut_mf

    < 24.1.9 | ≥ 25.0.2, < 25.0.12 | ≥ 26.0.2, < 26.0.4

  • papercut•papercut mf/ng

    < 24.1.10, 25.0.13, 26.0.5

  • papercut•papercut_ng

    < 24.1.9 | ≥ 25.0.2, < 25.0.12 | ≥ 26.0.2, < 26.0.4

References (3)