CVEs / CVE-2026-82078
CVE-2026-82078: PaperCut NG/MF Unsafe Reflection Vulnerability
- Known exploited in the CISA KEV catalog since 31 Aug 2026
- critical 9.1 CVSS 3.1 (NVD)
- EPSS 63% chance of exploitation in the next 30 days, higher than 99% of CVEs (30 Oct 2026)
- Last changed at its sources
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Summary
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.
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.
Affected and fixed versions
| Product | Affected | Fixed in |
|---|---|---|
| PaperCut PaperCut MF/NG | before 24.1.10 | 24.1.10 |
| PaperCut PaperCut MF/NG | from 25.0.0, before 25.0.13 | 25.0.13 |
| PaperCut PaperCut MF/NG | from 26.0.0, before 26.0.5 | 26.0.5 |
Exploitation
| In CISA KEV since | 31 Aug 2026 |
|---|---|
| Due date for US federal agencies | 14 Sep 2026 |
| Used in ransomware campaigns | Unknown |
| 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. |
Severity
| CVSS 3.1 | 9.1 criticalCVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:C/C:H/I:H/A:HScored by NVD |
|---|---|
| Weakness | CWE-470 |
References
- CVE-2026-82078 on NVD
- CVE-2026-82078 in the CISA KEV catalog
- https://www.papercut.com/kb/Main/security-bulletin-27-aug-2026-urgent-security-advisory/?lid=2oneu2wt0ct4 (cited by CISA)
- https://www.cisa.gov/news-events/directives/bod-26-04-prioritizing-security-updates-based-risk (cited by CISA)
- https://www.cisa.gov/news-events/directives/bod-26-04-implementation-guidance-prioritizing-security-updates-based-risk (cited by CISA)
- 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
Sources
Exploitation status from the CISA Known Exploited Vulnerabilities catalog. EPSS scores from FIRST. Descriptions, severity and references from the National Vulnerability Database. Open-source package versions from OSV (CC-BY 4.0). Text is shown as each source states it; Stackurity does not edit it. Check the vendor's advisory before acting.
This product uses data from the NVD API but is not endorsed or certified by the NVD.