CVE-2026-82078
PaperCut NG/MF Unsafe Reflection Vulnerability
Does this matter?
Known to be exploited in the wild (CISA KEV, CISA remediation deadline 14 September 2026). Treat as an emergency change: patch or isolate now, then hunt for prior compromise.
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.
- CVSS 4.0
- 9.4 CRITICALCVSS: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/M
- EPSS
- 60.89% probability · 99th percentile
- Public exploits
- None in Exploit-DB
- CISA KEV
- Listed 31 August 2026 · due 14 September 2026
- Weakness
- CWE-470
- Affected
- papercut/papercut mf · papercut/papercut ng
- Source
- eb41dac7-0af8-4f84-9f6d-0272772514f4
EPSS moved from 61.4% on 30 September 2026 to 60.9% on 29 October 2026, peaking at 63.5% on 8 October 2026. The dashed line is the ten per cent mark our analysts treat as “patch before the next change window”.
CISA notes
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. https://www.papercut.com/kb/Main/security-bulletin-27-aug-2026-urgent-security-advisory/?lid=2oneu2wt0ct4 ; BOD 26-04: https://www.cisa.gov/news-events/directives/bod-26-04-prioritizing-security-updates-based-risk ; Forensics Triage Requirements: https://www.cisa.gov/news-events/directives/bod-26-04-implementation-guidance-prioritizing-security-updates-based-risk ; https://nvd.nist.gov/vuln/detail/CVE-2026-82078
References
- https://www.papercut.com/kb/Main/security-bulletin-27-aug-2026-urgent-security-advisory/Patch, Vendor Advisory
- https://github.com/rapid7/metasploit-framework/pull/21842Issue Tracking, Patch
- https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2026-82078Patch, Third Party Advisory, US Government Resource
Source: NVD record, EPSS from FIRST.org, KEV from CISA, exploits from Exploit-DB. Refreshed daily. Download this record as JSON.