Vulnerability report

Exploited in the wild Confirmed confidence In CISA KEV

CVE-2026-81578

PaperCut MF/NG Authentication Bypass Authentication Bypass

PaperCut MF/NG · affected before 24.1.10

Watch CVE-2026-81578 Browse KEV feed
Severity
CVSS 8.8 · High
Confidence
Confirmed
Exploit status
Exploited in the wild
EPSS
85.6%
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 MF/NG. An improper access control vulnerability exists in the web management interface of PaperCut MF and PaperCut NG. Under specific conditions,...

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 MF/NG affected before 24.1.10.

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.

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

Tags

cisa nuclei_scanner

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

A trusted third party reported exploitation.

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
PaperCut Security Bulletins 2026-09-05 22:30 UTC
watchTowr 2026-10-09 18:20 UTC

Detection

Operational artifacts and observed signals

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

Observed signals

Request targets
User-Agents
Callback hosts
0
0
0

Request targets and User-Agents available in Pro. Callback host details available in Enterprise.

Virtual patch status

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

Learn about virtual patches →

Scanner Artifacts

Scanner and exploit-framework references linked to this CVE.

Scanner Reference Detected
Nuclei https://github.com/projectdiscovery/nuclei-templates/blob/main/http/cves/2026/CVE-2026-81578.yaml 16 Sep 2026

Risk and context

Severity, weaknesses, and research context

CVSS v4.0

8.8 High

Potential damage if exploited. Separate from whether attackers are using it.

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

85.6%

Estimated chance of exploitation in the next 30 days. Previdian's warning comes from evidence, not this score.

Weaknesses

Authentication Bypass by Primary Weakness CWE-305

Recent mention · watchTowr

Death By A Thousand PaperCuts (PaperCut Pre-Auth RCE Chain and Patch Bypasses WT-2026-0141-0144/CVE-2026-82077/CVE-2026-82078/CVE-2026-81578)

Before we begin, yes - it's confusing. There are more vulnerabilities with watchTowr IDs in this blog post than there are CVE IDs (assigned by PaperCut), due to PaperCut bundling vulnerabilities and then patch bypasses for those same vulnerabilities into singular CVE...

Read full advisory

All CVSS Scores

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

CVSS v3.1 9.8 Critical

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

All Mentions

Recent mention · watchTowr

Death By A Thousand PaperCuts (PaperCut Pre-Auth RCE Chain and Patch Bypasses WT-2026-0141-0144/CVE-2026-82077/CVE-2026-82078/CVE-2026-81578)

watchTowr · 09 Oct 2026

Before we begin, yes - it's confusing. There are more vulnerabilities with watchTowr IDs in this blog post than there are CVE IDs (assigned by PaperCut), due to PaperCut bundling vulnerabilities and then patch bypasses for those same vulnerabilities into singular CVE IDs.Paper! It still exists.We have

Recent mention · Rapid7

Metasploit Wrap Up: This One Goes to Sixteen!

Rapid7 · 11 Sep 2026

This One Goes to Sixteen!Another banger from Metasploit with sixteen new modules, including ten exploit modules, with five on the CISA KEV list. Cisco, Papercut, Sonicwall, Jetbrains, and Langflow all have exploit modules, and not to be outdone, we even have a Metasploit scanner to watch the watchers!New module content (16)Elasticsearch ingest-attachment Apache Tika XFA XXE Local File ReadAuthors: Bourbon Offensive Security Services and Jean-Marie BourbonType: AuxiliaryPull request: #21739 contributed by kmkzPath: scanner/http/elasticsearch_tika_xfa_xxeCVE...

Recent mention · TheRegister

Hundreds of AI agents helped PaperCut attacker hit 395+ orgs, and some went off script

TheRegister · 10 Sep 2026

Human operator: don't touch CIS orgs. AI agents: look a squirrel!

Recent mention · RecordedFuture

August 2026 CVE Landscape

RecordedFuture · 08 Sep 2026

In August 2026, Insikt Group® identified 73 high-impact vulnerabilities that should be prioritized for remediation, 43 of which had a Very Critical Recorded Future Risk Score. This represents a 14% decrease from last month.

Recent mention · PaperCut Security Bulletins

URGENT Security Advisory: PaperCut NG/MF Security Bulletin (27 Aug 2026)

PaperCut Security Bulletins · 05 Sep 2026

URGENT Security Advisory: PaperCut NG/MF Security Bulletin (27 Aug 2026) THE PAGE APPLIES TO: collapseMenuSize" id="toc-container" class="toc" :class="tocFullyScrolled ? 'toc--bottom' : 'toc--scrolling'" aria-label="Table of Contents"> Contents Overview URGENT Security Advisory Immediate action required Emergency Patch Release 3 Security issues addressed Who is potentially impacted Indicators of compromise and investigation guidance Current Status FAQs Security notifications Updates Contents Overview URGENT Security Advisory Immediate action required Emergency Patch Release 3 Security...

Recent mention · The Hacker News

Attackers Exploit PaperCut Flaws to Steal Credentials From Schools and Universities

The Hacker News · 05 Sep 2026

Threat actors are exploiting the newly disclosed PaperCut flaws to facilitate credential theft in attacks targeting the education sector in the U.S. and Europe. The Arctic Wolf Adversary Research Team said it observed attackers exploiting CVE-2026-81578 and CVE-2026-82078 – an authentication bypass and remote code execution chain – to conduct command execution and reconnaissance, as well as

Recent mention · Rapid7

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

Rapid7 · 28 Aug 2026

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 emergency. At the initial time of disclosure, the vulnerability had not been assigned a CVE identifier, and PaperCut had not publicly disclosed a CVSS score, vulnerability class, authentication requirements, or the technical details of the exploit path. However on August 28, the vendor assigned CVE-2026-81578 and...

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

PaperCut NG/MF <=26.0.4 - Unauthenticated ConfigEditor Access via Tapestry Complex-Direct

nuclei · Created Unknown

Timeline

From disclosure to observed exploitation

  1. 18:20 UTC

    KEV confirmed by watchTowr

    Exploitation attested by an external source

  2. 04:30 UTC

    Nuclei template available

    Scanner coverage available

  3. 22:30 UTC

    KEV confirmed by PaperCut Security Bulletins

    Exploitation attested by an external source

  4. 15:42 UTC

    KEV confirmed by CVE

    Exploitation attested by an external source

  5. 14:20 UTC

    Added to CISA KEV

    Listed in the CISA Known Exploited Vulnerabilities catalog

  6. 13:12 UTC

    Public PoC available

    Public proof-of-concept code published

  7. 11:39 UTC

    CVE published

    Vulnerability disclosed publicly

  8. 10:09 UTC

    KEV confirmed by Rapid7

    Exploitation attested by an external source

  9. 15:39 UTC

    Added to Previdian KEV Feed

    High-confidence, third-party attested exploitation

  10. 07:34 UTC

    CVE ID reserved

    Identifier reserved by the CNA

Pro API

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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
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  • Affected versions and enrichment
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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": 0.85581,
  "exploit_status": {
    "exploited_in_the_wild": true,
    "active_exploitation_observed": false
  },
  "sensor_telemetry": { "attempts": 0, "sensors": 0 }
}