---
id: "CVE-2026-82078"
kind: "vulnerability"
aliases: ["CVE-2026-82078"]
title: "An unsafe dynamic class loading vulnerability exists in the database connection utilities of PaperCut MF and PaperCut NG"
severity: "critical"
cvss: 9.4
epss: null
exploited: true
status: "open"
category: "vendor"
products: [{"name": "PaperCut NG/MF", "fixed": [], "affected": "", "ecosystem": "vendor"}, {"name": "PaperCut NG", "fixed": ["26.0.5", "25.0.13", "24.1.10"], "affected": "all versions before 26.0.5 / 25.0.13 / 24.1.10", "ecosystem": "vendor"}, {"name": "PaperCut MF", "fixed": ["26.0.5", "25.0.13", "24.1.10"], "affected": "all versions before 26.0.5 / 25.0.13 / 24.1.10", "ecosystem": "vendor"}, {"name": "papercut mf", "fixed": ["24.1.9"], "affected": "< 24.1.9", "ecosystem": "vendor"}, {"name": "papercut mf", "fixed": ["25.0.12"], "affected": ">= 25.0.2, < 25.0.12", "ecosystem": "vendor"}, {"name": "papercut mf", "fixed": ["26.0.4"], "affected": ">= 26.0.2, < 26.0.4", "ecosystem": "vendor"}, {"name": "papercut ng", "fixed": ["24.1.9"], "affected": "< 24.1.9", "ecosystem": "vendor"}, {"name": "papercut ng", "fixed": ["25.0.12"], "affected": ">= 25.0.2, < 25.0.12", "ecosystem": "vendor"}, {"name": "papercut ng", "fixed": ["26.0.4"], "affected": ">= 26.0.2, < 26.0.4", "ecosystem": "vendor"}]
ecosystems: ["vendor"]
tags: ["exploited", "papercut-mf", "papercut-ng", "print-server", "rce", "self-hosted", "vendor"]
not_affected_if: ["managed-hosting"]
published_at: "2026-08-28T16:18:31+00:00"
first_seen_at: "2026-10-23T19:11:51+00:00"
updated_at: "2026-10-23T23:44:52+00:00"
sources: [{"source": "kev", "url": "https://www.cisa.gov/known-exploited-vulnerabilities-catalog?search_api_fulltext=CVE-2026-82078", "first_seen_at": "2026-10-23T19:11:51+00:00"}, {"source": "analyst", "url": null, "first_seen_at": "2026-10-23T21:31:40+00:00"}, {"source": "nvd", "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-82078", "first_seen_at": "2026-10-23T23:44:52+00:00"}]
---

# An unsafe dynamic class loading vulnerability exists in the database connection utilities of PaperCut MF and PaperCut NG

PaperCut NG/MF unsafe class loading in the database connector (CWE-470). Driver class names come from configuration with no allowlist, so arbitrary classpath bytecode runs as the PaperCut server process. It is chained in the wild with CVE-2026-81578, an unauthenticated config change, which gives unauthenticated RCE. Attackers have dropped SimpleHelp and AnyDesk after exploitation. All NG and MF versions are affected.

_Summary, check and fix written by a model from the sources; labelled as such._

## Affected

- vendor:PaperCut NG/MF affected ? fixed ?
- vendor:PaperCut NG affected all versions before 26.0.5 / 25.0.13 / 24.1.10 fixed 26.0.5, 25.0.13, 24.1.10
- vendor:PaperCut MF affected all versions before 26.0.5 / 25.0.13 / 24.1.10 fixed 26.0.5, 25.0.13, 24.1.10
- vendor:papercut mf affected < 24.1.9 fixed 24.1.9
- vendor:papercut mf affected >= 25.0.2, < 25.0.12 fixed 25.0.12
- vendor:papercut mf affected >= 26.0.2, < 26.0.4 fixed 26.0.4
- vendor:papercut ng affected < 24.1.9 fixed 24.1.9
- vendor:papercut ng affected >= 25.0.2, < 25.0.12 fixed 25.0.12
- vendor:papercut ng affected >= 26.0.2, < 26.0.4 fixed 26.0.4

## How to check

Check the Application Server version in the admin UI. Anything below 26.0.5, 25.0.13 or 24.1.10, or on Emergency Patch Release 1 or 2, is exposed. Look in server.log for 'No suitable driver found for jdbc:no:x', 'DB URL: jdbc:derby:memory:pwn;create=true', 'Database error looking up cardID: VALUES CAST', or missing or truncated server.log. Look for files server\lib\<5char>.class and server\data\content\<5char>.cmd or .out. Check for pc-app spawning cmd.exe, a Windows service 'Remote Access Service' (SimpleService.exe) and unexpected AnyDesk installs.

## Fix

Upgrade to PaperCut NG/MF 26.0.5, 25.0.13 or 24.1.10 (these replace the emergency patches; Emergency Patch Release 3 is protective). Update Site Servers and secondary servers too. Until then, firewall the Application Server from the internet. If you suspect compromise, rebuild the server and restore a clean backup.

## Timeline

- 2026-10-23T19:11:51+00:00 kev https://www.cisa.gov/known-exploited-vulnerabilities-catalog?search_api_fulltext=CVE-2026-82078
- 2026-10-23T21:31:40+00:00 analyst — PaperCut bulletin of 27 Aug 2026 (updated 10 Sep) read. All NG/MF versions affected; fixed in 26.0.5, 25.0.13, 24.1.10 (Emergency Patch Release 3 also mitigates). CVSS 4.0 9.4 from the vendor. Chained with CVE-2026-81578 (unauthenticated config change) for RCE. No public PoC found. The 'older than v24' fix version is unknown; the vendor only says upgrade to latest.
- 2026-10-23T23:44:52+00:00 nvd https://nvd.nist.gov/vuln/detail/CVE-2026-82078

## Documents

- [advisory] PaperCut NG/MF Security Bulletin (27 Aug 2026), updated 10 Sep https://www.papercut.com/kb/Main/security-bulletin-27-aug-2026-urgent-security-advisory/
- [describes] UofT advisory: PaperCut NG and MF https://security.utoronto.ca/advisories/security-advisory-papercut-ng-and-papercut-mf/
- [mentions] Canadian Cyber Centre AV26-858 https://www.cyber.gc.ca/en/alerts-advisories/papercut-security-advisory-av26-858
- [poc] Metasploit module for CVE-2026-81578 + CVE-2026-82078 (merged 2026-09-03) https://github.com/rapid7/metasploit-framework/pull/21842

## From the sources

PaperCut NG/MF contains an unsafe reflection vulnerability that allows an attacker to manipulate system configuration parameters and execute arbitrary Java bytecode residing on the application classpath under the security context of the PaperCut server process. This vulnerability can be chained with CVE-2026-81578.

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.

---

_Free to read at a human pace. An API with keys and an MCP server are in preparation; early access: hello@infrastack.ai_