CVE-2026-82078

PaperCut NG/MF: Unsafe Reflection

As of , CVE-2026-82078 in PaperCut NG/MF is on CISA's list of exploited vulnerabilities: CISA listed it on . Our patch-first group: Patch this week.

Exploited
Yes: CISA listed it on 31 August 2026
US federal deadline
14 September 202614 days after CISA listed it. US federal civilian agencies must fix it by then.
Used in ransomware campaigns
Not known to CISA
EPSS score
0.61Higher than 99% of the CVEs EPSS scores. EPSS estimates the chance of exploitation activity in the next 30 days.
Public exploit
1 Metasploit module
Fix
Vendor advice: www.papercut.comLinks below, from CISA's entry.

What CISA says to do

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's required action

What the flaw is

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's description

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.

The CVE record's description, from PaperCut

CVE published
28 August 2026
Assigned by
PaperCut
CVSS
9.4 Critical (CVSS 4.0, from the CNA)
CWE-470
Use of Externally-Controlled Input to Select Classes or Code ('Unsafe Reflection')
CISA SSVC, exploitation
active
CISA SSVC, automatable
no
CISA SSVC, technical impact
total

Timeline

  1. The CVE record was published.
  2. CISA added it to its list of exploited vulnerabilities.
  3. The US federal deadline to fix it.

Public exploits

Facts from Metasploit's module list and Exploit-DB's index; we never copy exploit code.

  • Metasploit: PaperCut NG/MF Unauthenticated RCE (CVE-2026-81578 + CVE-2026-82078)exploit module, rank excellent

NG/MF: other exploited entries

VulnerabilityProductOur groupListedDeadlineEPSS
CVE-2023-27351Improper AuthenticationPaperCut NG/MFPatch nowRansomware use, listed within a year0.78
CVE-2026-81578Missing Authentication for Critical FunctionPaperCut NG/MFPatch this weekMetasploit module; EPSS 0.850.85
CVE-2023-2533Cross-Site Request Forgery (CSRF)PaperCut NG/MFPatch soon0.29

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