CVE-2026-82078: PaperCut NG/MF Unsafe Reflection Vulnerability
PaperCut · NG/MF · NVD published 2026-08-28 · posted 2026-08-31 · last modified 2026-09-14
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.
| Weakness | CWE-470 |
|---|---|
| CVSS vector | 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/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X (source: eb41dac7-0af8-4f84-9f6d-0272772514f4) |
| CISA due date | 2026-09-14 (for US federal agencies under BOD; a good deadline for everyone) |
| ATT&CK tactics | n/a |
Exploitation evidence
First exploit evidence seen: 2026-08-27 (earliest date across the sources below).
Exploited in the wild
- CISA KEV: listed since 2026-08-31. Source
Public exploit code
Metasploit
exploit/multi/http/papercut_ng_external_user_lookup_rce: PaperCut NG/MF Unauthenticated RCE (CVE-2026-81578 + CVE-2026-82078) (disclosure 2026-08-27)
Sources: CISA KEV · Rapid7 Metasploit Framework module metadata.
No ATT&CK techniques could be mapped or inferred for this CVE yet.
How to fix it
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. (source: CISA KEV)
Fixed versions
- papercut papercut mf: upgrade to 24.1.9 or later
- papercut papercut mf: upgrade to 25.0.12 or later (affected from 25.0.2)
- papercut papercut mf: upgrade to 26.0.4 or later (affected from 26.0.2)
- papercut papercut ng: upgrade to 24.1.9 or later
- papercut papercut ng: upgrade to 25.0.12 or later (affected from 25.0.2)
- papercut papercut ng: upgrade to 26.0.4 or later (affected from 26.0.2)
Derived from the NVD CPE configuration (versionEndExcluding / versionEndIncluding). Always confirm with the vendor advisory.
Vendor advisories and patches
- https://www.papercut.com/kb/Main/security-bulletin-27-aug-2026-urgent-security-advisory/?lid=2oneu2wt0ct4 (CISA KEV notes)
- https://www.papercut.com/kb/Main/security-bulletin-27-aug-2026-urgent-security-advisory/ (Patch, Vendor Advisory)
- https://github.com/rapid7/metasploit-framework/pull/21842 (Issue Tracking, Patch)
- https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2026-82078 (Patch, Third Party Advisory, US Government Resource)
Detection Generic guidance
Response checklist Generic guidance
- Inventory: find every instance of the affected product and version (include internet-facing and forgotten ones).
- Patch or mitigate per the vendor advisory; if you cannot patch, remove internet exposure or apply the vendor workaround.
- Assume compromise if the system was exposed before patching: hunt for the indicators in the advisory and review logs back to the disclosure date.
- Rotate credentials and secrets stored on or used by the affected system if compromise cannot be ruled out.