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CVE-2026-81578

9.8, critical Known exploited

PaperCut NG/MF Missing Authentication for Critical Function Vulnerability

NVD (opens in a new tab) CVE.org (opens in a new tab) CISA KEV catalogue (opens in a new tab)
CVSS
9.8, critical critical CVSS v3.1
EPSS, next 30 days
86% higher than 99.7% of scored CVEs
Exploitation
Confirmed in the wild
Published
28 Aug 2026a month ago

Known exploited

CISA added this to the Known Exploited Vulnerabilities Catalog on 31 Aug 2026. US federal agencies had to remediate by 14 Sept 2026, a deadline that has passed.

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.

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.

Details

Vendor
PaperCut
Product
PaperCut MF/NG
Weakness
CWE-305 (opens in a new tab)
Status
Analyzed
Updated
14 Sept 2026
Assigner
eb41dac7-0af8-4f84-9f6d-0272772514f4

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

References 3

Patches and fixes 3

The kind is read from NVD's tags where present and from the shape of the URL otherwise, so treat it as a hint.

Other PaperCut CVEs

Every PaperCut CVE we hold

Same vendor in what we hold, not a known link between the flaws.

  • CVE-2026-82078 PaperCut NG/MF Unsafe Reflection Vulnerability KEV EPSS 64% 9.1, critical
  • CVE-2023-2533 PaperCut NG/MF Cross-Site Request Forgery (CSRF) Vulnerability KEV EPSS 29% 8.8, high
  • CVE-2023-27350 PaperCut MF/NG Improper Access Control Vulnerability KEV EPSS 100% 9.8, critical
  • CVE-2023-27351 PaperCut NG/MF Improper Authentication Vulnerability KEV EPSS 78% 7.5, high

Beyond this page

Is CVE-2026-81578 in your network?

This page tells you how dangerous CVE-2026-81578 is out there. Whether it sits on one of your devices, only a scan of your own network can tell. That is what our systems do, every day, for the companies we protect.

CVE-2026-81578 is in the CISA catalogue of exploited vulnerabilities: attackers are already exploiting it.

  • EXYS7600 OCELOT

    Find it before attackers do

    Ocelot scans your network on a schedule and reports every vulnerability it finds by its CVE identifier, with its CVSS score and how many of your hosts are affected. A finding like CVE-2026-81578 comes with the devices to patch.

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  • EXYS7950 KONDRA

    Detect it if it's exploited

    Until the patch is applied, Kondra monitors your network, events and endpoints in real time. It keeps an inventory of the software installed on every endpoint, and its anomaly detection rules flag what an attacker does once inside.

    Learn more about EXYS7950 KONDRA
Check your exposure

Assembled from the NVD 2.0 API, the CISA Known Exploited Vulnerabilities Catalog and FIRST EPSS. Scores are as of our last collection on 17 Oct 2026, not the live upstream state.