CVE-2026-81578

Published Aug 28, 2026

Last updated a month ago

Exploit known CVSS high 8.8

web application

Cloud

SMTP

PaperCut MF

PaperCut NG

Overview

AI description

Automated description summarized from trusted sources.

CVE-2026-81578 describes an improper access control vulnerability found in the web management interface of PaperCut MF and PaperCut NG. This flaw allows unauthenticated remote requests, specifically those targeting administrative functions, to initiate backend actions before the system fully completes its access validation checks. The vulnerability, categorized as CWE-306 (Missing authentication for critical function), enables an unauthenticated remote attacker to modify certain system configurations. It has been observed to be actively exploited in the wild, often in conjunction with CVE-2026-82078, to achieve broader compromise.

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.
Source: eb41dac7-0af8-4f84-9f6d-0272772514f4
NVD status: Analyzed
Products: papercut_mf, papercut_ng

Risk scores

CVSS 4.0

Type: Secondary
Base score: 8.8
Impact score: -
Exploitability score: -
Vector string: 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
Severity: HIGH

CVSS 3.1

Type: Primary
Base score: 9.8
Impact score: 5.9
Exploitability score: 3.9
Vector string: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Severity: CRITICAL

Known exploits

Data from CISA

Vulnerability name: PaperCut NG/MF Missing Authentication for Critical Function Vulnerability
Exploit added on: Aug 31, 2026
Exploit action due: Sep 14, 2026
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.

Weaknesses

eb41dac7-0af8-4f84-9f6d-0272772514f4: CWE-305

Hype score: Not currently trending

Configurations

[
  {
    "nodes": [
      {
        "cpeMatch": [
          {
            "criteria": "cpe:2.3:a:papercut:papercut_mf:*:*:*:*:*:*:*:*",
            "matchCriteriaId": "F2AF3AB4-FD10-4DE1-B906-011F45948BD0",
            "versionEndExcluding": "24.1.9",
            "vulnerable": true
          },
          {
            "criteria": "cpe:2.3:a:papercut:papercut_mf:*:*:*:*:*:*:*:*",
            "matchCriteriaId": "8F6ED0B8-62DC-4CF9-9810-2CCB824FBCA8",
            "versionEndExcluding": "25.0.12",
            "versionStartIncluding": "25.0.2",
            "vulnerable": true
          },
          {
            "criteria": "cpe:2.3:a:papercut:papercut_mf:*:*:*:*:*:*:*:*",
            "matchCriteriaId": "51E91B81-E311-4BB9-A753-671F0C59E7F7",
            "versionEndExcluding": "26.0.4",
            "versionStartIncluding": "26.0.2",
            "vulnerable": true
          },
          {
            "criteria": "cpe:2.3:a:papercut:papercut_ng:*:*:*:*:*:*:*:*",
            "matchCriteriaId": "44FCDCDE-4126-4F4F-89FC-D44924F45C82",
            "versionEndExcluding": "24.1.9",
            "vulnerable": true
          },
          {
            "criteria": "cpe:2.3:a:papercut:papercut_ng:*:*:*:*:*:*:*:*",
            "matchCriteriaId": "9E727ABD-0007-424D-AB07-FB7816E43792",
            "versionEndExcluding": "25.0.12",
            "versionStartIncluding": "25.0.2",
            "vulnerable": true
          },
          {
            "criteria": "cpe:2.3:a:papercut:papercut_ng:*:*:*:*:*:*:*:*",
            "matchCriteriaId": "3938B71A-CB14-4017-A037-7D5F08DAFB13",
            "versionEndExcluding": "26.0.4",
            "versionStartIncluding": "26.0.2",
            "vulnerable": true
          }
        ],
        "negate": false,
        "operator": "OR"
      }
    ]
  }
]

References

Sources include official advisories and independent security research.