VULNpocalypse

CVE-2026-81578: PaperCut NG/MF Missing Authentication for Critical Function Vulnerability

Advisory generated from the CVE record, CISA, Exploit Observer and VEDAS: what it is, whether it is exploited, who is affected, and how to fix and detect it.

Generated by VEDAS. Scores as of 2026-11-01 19:19 UTC. Rebuilt every few hours from cve-scores, CISA KEV and vedas-signatures. How this works and its limits.

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.

Description quoted from the CVE record (assigned by PaperCut, published 2026-08-28).

Weakness: CWE-305 Authentication bypass by primary weakness

How it can be exploited

Exploitable over the network with low attack complexity with no special attack requirements needing no privileges and no user interaction. Impact: confidentiality low, integrity high, availability low. 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

CISA assessment (SSVC): CISA assesses exploitation as active. Automatable: yes. Technical impact: partial.

On CISA KEV since
2026-08-31
US federal deadline
2026-09-14
Ransomware use
Not known

Public exploit evidence (Exploit Observer)

Also known as: BDU:2026-15087, EUVD-2026-67713, GHSA-44wc-j6f2-7fjr

VEDAS cluster: VEDAS:BARMYBADGER

Exploit Observer links 7 pieces of public exploit code or detection modules that name this CVE or one of its aliases.

Exploit code and modules (7)

Code that names this CVE. A repository can be a working exploit, a scanner, a fake or malware; read it before running anything.

Research and write-ups (5)

Vulnerability databases and vendor advisories (6)

Catalogue entries, not exploit evidence.

156 more references returned by Exploit Observer did not name this CVE or an alias, so they are left out.

VEDAS data as of 2026-11-01T17:12 UTC; fetched 2026-11-02.

Live scores

EPSS
0.847
very likely to be attacked soon
VEDAS
0.988
strong exploit evidence
On CISA KEV
Yes, since 2026-08-31
Detection rule
Nuclei · Suricata
EPSS (chance of attack)
100.1Added to CISA KEV 2026-08-31CVE-2026-81578 EPSS over time2026-082026-11-01
VEDAS (exploit evidence)
100.9Added to CISA KEV 2026-08-31CVE-2026-81578 VEDAS over time2026-082026-11-01

Thin horizontal line: the “likely” (EPSS 0.10) or “strong” (VEDAS 0.90) threshold. Shaded “no data” areas are periods when cve-scores did not publish. The vertical line is the day CISA added it to its exploited list.

VEDAS flagged this bug about 2 days before CISA confirmed attacks.

Who is affected

ProductAffectedNot affected
PaperCut PaperCut MF/NGbefore 24.1.10
from 25.0.0 before 25.0.13
from 26.0.0 before 26.0.5		Not stated

Version ranges exactly as the CVE record states them. “Before X” means X is the first fixed version.

Exploit Observer also maps it to: papercut papercut_mf, papercut papercut_ng, papercut_software_international_pty_ltd papercut_mf, papercut_software_international_pty_ltd papercut_ng.

How to fix it

Fixed versions stated in the CVE record: 24.1.10, 25.0.13, 26.0.5.

CISA 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.

Vendor guidance:

How to detect it

Nuclei template (active check)

PaperCut MF - Missing Authentication

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.

Name and description quoted from the template, written by VEDAS.

The template sends 5 requests (GET /app?service=page/Error, GET /app, POST /app?service=direct/{{rand}}/Home/ConfigEditor/quickFindForm, GET / and 1 more); it decides using dsl matchers. Severity in the template: critical. Marked as not yet verified against a live vulnerable target.

Run it against a host you own or are authorised to test:

bash
nuclei -u https://your-host -t CVE-2026-81578.yaml
Show the template (75 lines)
yaml
id: CVE-2026-81578

info:
  name: "PaperCut MF - Missing Authentication"
  author: vedas-arpsyndicate
  severity: critical
  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.
  reference:
    - https://www.exploit.observer/?keyword=CVE-2026-81578&match=exact
    - https://subdomain.center/?engine=ammonites&keyword=papercut&match=exact
  classification:
    cvss-metrics: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
    cvss-score: 9.8
    cve-id: CVE-2026-81578
    cwe-id: CWE-306
  metadata:
    verified: false
  tags: cve,cve2026,papercut,auth-bypass,rce,unauth,tapestry,kev,vkev
variables:
  rand: "{{rand_text_alpha(8)}}"

flow: http(1) && http(2) && http(3)

http:
  - raw:
      - |
        GET /app?service=page/Error HTTP/1.1
        Host: {{Hostname}}

    host-redirects: true
    max-redirects: 2

    matchers:
      - type: dsl
        dsl:
          - 'contains(body, "<!-- Page: Error -->")'
          - 'status_code == 200'
        condition: and
        internal: true

  - raw:
      - |
        GET /app HTTP/1.1
        Host: {{Hostname}}

    host-redirects: true
    max-redirects: 2

    matchers:
      - type: dsl
        internal: true
        dsl:
          - 'contains(body, "<!-- Page: Home -->")'
          - 'status_code == 200'
        condition: and

  - raw:
      - |
        POST /app?service=direct/{{rand}}/Home/ConfigEditor/quickFindForm HTTP/1.1
        Host: {{Hostname}}
        Content-Type: application/x-www-form-urlencoded
        Origin: {{RootURL}}
        Referer: {{RootURL}}/app

        sp=S0&Form0=%24TextField%2CdoQuickFind%2Cclear&%24TextField=server.name&doQuickFind=Go

    matchers:
      - type: dsl
        dsl:
          - 'contains(body, "<!-- Page: Home -->")'
          - 'status_code == 200'
        condition: and

CVE-2026-81578.yaml on GitHub

Suricata rules (network detection)

1 rule that alert on traffic matching this exploit: VEDAS CVE-2026-81578 PaperCut MF - Missing Authentication. Add them to your Suricata rule set and reload.

Show the rules
suricata
alert http $EXTERNAL_NET any -> $HTTP_SERVERS $HTTP_PORTS (msg:"VEDAS CVE-2026-81578 PaperCut MF - Missing Authentication"; flow:established,to_server; http.request_body; content:"sp=S0&Form0=%24TextField%2CdoQuickFind%2Cclear&%24TextField="; nocase; fast_pattern; classtype:web-application-attack; reference:cve,CVE-2026-81578; reference:url,https://www.exploit.observer/?keyword=CVE-2026-81578&match=exact; reference:url,https://subdomain.center/?engine=ammonites&keyword=papercut&match=exact; sid:1011639; rev:1;)

CVE-2026-81578.rules on GitHub

References

Exploits and technical analysis

Government sources

Other references

Other databases

Where this comes from

This advisory is generated automatically by VEDAS from: CVE.org record, CISA KEV, cve-scores (EPSS and VEDAS), Exploit Observer, vedas-signatures. Text in quotes is reproduced from the source; everything else is a fixed template filled with source fields. Nothing here is written by a language model. Check the vendor advisory before acting, and read how VEDAS and Exploit Observer work, and their limits.