CVE-2026-82078: PaperCut NG/MF (Critical, CVSS 9.4)
- CVSS
- 9.4 Critical (v4.0)
- EPSS
- 63.5% chance of exploitation in the next 30 days (higher than 99.2% of CVEs)
- Exploited in the wild
- Yes, on CISA’s KEV list since Aug 31, 2026
- Public exploit
- Yes, reported in a Metasploit module
- Weakness
- CWE-470
- 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- Published
- Aug 28, 2026
- CISA fix-by date
- Sep 14, 2026 (for US federal agencies)
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.
Description from the National Vulnerability Database.
What to do
CISA: 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
Check whether you run PaperCut NG/MF, then apply the vendor’s fix or mitigation from the advisories below. Because this flaw is exploited or has public exploit code, treat it as urgent and check for signs of compromise, not just the patch level.
Advisories and fixes
ThreatRoundup coverage
PaperCut Attacker Left an AI Hacking Workbench Wide Open
Sources: NVD, FIRST EPSS, CISA KEV, and public exploit databases (availability only). ThreatRoundup reports whether public exploit code exists but never links to it: fake proof-of-concepts that infect security researchers are common. This page updates automatically.