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Vulnerability report

Exploited in the wild Confirmed confidence In CISA KEV

CVE-2026-81578

PaperCut MF/NG Authentication Bypass Authentication Bypass

PaperCut / PaperCut MF/NG · affected before 24.1.10, 25.0.13, 26.0.5

View live feed Monitor via API Watch CVE-2026-81578
Severity
CVSS 8.8 · High
Confidence
Confirmed
Exploit status
Exploited in the wild
EPSS
0.8%
First observed
—
Last observed
—

Decision summary

What security teams need to know first

Direct answers before the deeper technical record.

What it is

CVE-2026-81578 is an unauthenticated vulnerability affecting PaperCut PaperCut MF/NG. An improper access control vulnerability exists in the web management interface of PaperCut MF and PaperCut NG. Under...

Is it exploited?

Yes. Previdian tracks this CVE as a known exploited vulnerability. Confidence is confirmed. Listed in CISA KEV. Also confirmed by third-party sources.

Who is affected?

PaperCut / PaperCut MF/NG affected before 24.1.10, 25.0.13, 26.0.5.

What should we do?

Prioritize remediation. Validate affected assets and apply vendor fixes on an accelerated timeline.

Overview

An improper access control vulnerability exists in the web management interface of PaperCut MF and PaperCut NG

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.

Vendor Product Affected Status
PaperCut PaperCut MF/NG Before 24.1.10, 25.0.13, 26.0.5 Affected
Published
28 Aug 2026
Exploitation Reported
27 Aug 2026
Attack vector
Remote
Complexity
Low
Privileges
None
User interaction
None

Tags

cisa

CVE References

Exploitation evidence

Why Previdian marks this CVE as exploited

Third-party attestation and first-party sensor observation are shown separately so teams can judge the evidence chain.

Exploited in the wild

PaperCut

Recorded 27 Aug 2026

Independent exploitation attestation added to the Previdian record.

Proof of concept available

GitHub

Recorded 29 Aug 2026

Public scanner or PoC coverage increases practical exploitability.

Known exploited vulnerability sources

Per-source evidence links for KEV attestations are available through the Previdian Pro API.

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Source Added
PaperCut First 2026-08-27 15:39 UTC
Rapid7 2026-08-28 10:09 UTC
CISA 2026-08-31 14:20 UTC
CVE 2026-08-31 15:42 UTC

Detection

Operational artifacts and observed signals

Make the evidence actionable in scanner, SOC, and edge-control workflows.

Observed signals

Request targets
0
User-Agents
0

Raw values available in Pro and Enterprise.

Scanner coverage

No scanner integrations recorded yet.

Virtual patch status

No Previdian virtual patch is currently available. Future rules ship for ModSecurity, Cloudflare, and AWS WAF.

Learn about virtual patches →

No detection artifacts or sensor request patterns are available for this CVE yet.

Check back as sensor telemetry and scanner integrations are updated.

Risk and context

Severity, weaknesses, and research context

CVSS v4.0

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

EPSS

0.8%

Weaknesses

Authentication Bypass by Primary Weakness CWE-305

Recent mention · Rapid7

PaperCut NG/MF Critical Zero-Day Exploited in the Wild

Overview On August 27, 2026, PaperCut Software published an urgent security advisory stating that it is investigating active exploitation of a vulnerability affecting PaperCut NG and PaperCut MF. PaperCut has confirmed customer incidents and is treating the issue as a security...

Read full advisory

Potential Proof of Concepts

These PoCs are unverified and could contain malware. Use at your own risk.

PaperCut NG/MF CVE-2026-81578 + CVE-2026-82078 unauthenticated RCE chain

pruva · Created 2026-08-31 05:51:20 UTC

Severity: CRITICAL | CVE: CVE-2026-81578 | Package: PaperCut NG/MF

yora1928/PaperCut-CVE-2026-81578-82078

github · Created 2026-08-29 13:12:33 UTC · 0 stars · AI assessment 85%

Security research tool for PaperCut CVE-2026-81578 & CVE-2026-82078

CVE Record exploit — github.com

cve · Created Unknown

Timeline

From disclosure to observed exploitation

  1. KEV confirmed by CVE

    Exploitation attested by an external source

  2. Added to CISA KEV

    Listed in the CISA Known Exploited Vulnerabilities catalog

  3. Public PoC available

    Public proof-of-concept code published

  4. CVE published

    Vulnerability disclosed publicly

  5. KEV confirmed by Rapid7

    Exploitation attested by an external source

  6. Added to Previdian KEV Feed

    High-confidence, third-party attested exploitation

  7. CVE ID reserved

    Identifier reserved by the CNA

Pro API

Automate this intelligence

Confidence, exploit status, sensor telemetry, PoCs, scanner integrations, mentions, and tags are available programmatically for VM, SOC, and CTI workflows.

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  • Evidence confidence and provenance
  • First-party sensor telemetry
  • PoC and scanner references
  • Affected versions and enrichment
  • Automation-ready JSON delivery

GET /api/v2/pro/kevs/CVE-2026-81578

Free JSON includes basic KEV fields 
{
  "cve_id": "CVE-2026-81578",
  "confidence": "Confirmed",
  "cvss_score": 8.8,
  "cvss_estimated": false,
  "epss_score": 0.00771,
  "exploit_status": {
    "exploited_in_the_wild": true,
    "active_exploitation_observed": false
  },
  "sensor_telemetry": { "attempts": 0, "sensors": 0 }
}