---
title: "CVE-2026-82078: PaperCut NG/MF Unsafe Reflection Vulnerability"
url: https://erroneo.us/security/cve/CVE-2026-82078/
description: "CVE-2026-82078 (PaperCut NG/MF): Exploited in the wild (CISA KEV). An unsafe dynamic class loading vulnerability exists in the database connection utilities…"
type: vulnerability-record
section: "Security Digest"
date_published: 2026-08-28
date_modified: 2026-10-21
publisher: erroneo.us
author: erroneo.us Security Desk
cve: "CVE-2026-82078"
kev: true
cvss: 9.4
epss: 0.63532
license: All rights reserved. Quote with attribution and a link.
---

# CVE-2026-82078: PaperCut NG/MF Unsafe Reflection Vulnerability

**Signal:** Exploited: patch now if you run it. CISA has confirmed exploitation in the wild. (Computed from CISA KEV, EPSS and CVSS; not an editorial verdict.)

## Should you act?

- Yes, if you run PaperCut NG/MF. CISA added this CVE to its Known Exploited Vulnerabilities catalog on 2026-08-31, which means there is reliable evidence of exploitation in the wild. US federal agencies must remediate by 2026-09-14 ; treat that as the outer limit, not the target.
- EPSS 63.5% , percentile 99: FIRST’s model estimates a 63.5% chance of exploitation activity in the next 30 days, higher than 99% of all scored CVEs (very high). EPSS is a probability, not a verdict.
- Needs an account (high (admin)). Exposure depends on who can log in.
- Editorial verdict: Act now. PaperCut NG/MF: Mass-Exploited Pre-Auth RCE Chain (KEV) — If a PaperCut NG/MF server below 24.1.10, 25.0.13 or 26.0.5 was reachable from the internet after late August, assume it was compromised: upgrade, then hunt and rebuild, because this chain gave unauthenticated attackers SYSTEM and was mass-exploited.

## What it is

An unsafe dynamic class loading vulnerability exists in the database connection utilities of PaperCut MF and PaperCut NG. The application instantiates database driver classes based on configurable driver names without validating against an allowlist of approved drivers. If an attacker can manipulate system configuration parameters, this enables the execution of arbitrary Java bytecode residing on the application classpath under the security context of the PaperCut server process.

## Affected products (CVE record)

- PaperCut PaperCut MF/NG: < 24.1.10, 25.0.0 < 25.0.13, 26.0.0 < 26.0.5

## Severity

- PaperCut CVSS 4.0: 9.4 `CVSS:4.0/AV:N/AC:L/AT:N/PR:H/UI:N/VC:H/VI:H/VA:H/SC:H/SI:H/SA:H`

## Exploitation

- CISA KEV: added 2026-08-31; federal due date 2026-09-14. Known ransomware use: Unknown.
- 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.
- CISA SSVC assessment: exploitation active , automatable no , technical impact total .
- FIRST EPSS (model of 2026-10-21): 63.53% probability of exploitation activity in the next 30 days; percentile 99.

## Sources

- [Listed in CISA KEV notes (papercut.com)](https://www.papercut.com/kb/Main/security-bulletin-27-aug-2026-urgent-security-advisory/?lid=2oneu2wt0ct4)
- [CVE.org record CVE-2026-82078](https://www.cve.org/CVERecord?id=CVE-2026-82078)
- [NVD entry CVE-2026-82078](https://nvd.nist.gov/vuln/detail/CVE-2026-82078)
- [CISA Known Exploited Vulnerabilities catalog entry](https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2026-82078)
- [Listed in CISA KEV notes (cisa.gov)](https://www.cisa.gov/news-events/directives/bod-26-04-prioritizing-security-updates-based-risk)
- [Listed in CISA KEV notes (cisa.gov)](https://www.cisa.gov/news-events/directives/bod-26-04-implementation-guidance-prioritizing-security-updates-based-risk)
- [papercut.com](https://www.papercut.com/kb/Main/security-bulletin-27-aug-2026-urgent-security-advisory/)
- [github.com](https://github.com/rapid7/metasploit-framework/pull/21842)

---
Source page: https://erroneo.us/security/cve/CVE-2026-82078/ · Security Digest: https://erroneo.us/security/ · More: https://erroneo.us/llms.txt