CVE-2026-82078PaperCut NG/MF Unsafe Reflection Vulnerability
CVE-2026-82078 is a unsafe reflection in PaperCut NG/MF, rated critical (9.4 on CVSS 4.0).
Why this priority: Exploited in the wild: listed in CISA's KEV catalog.
Published · Updated · NVD status: Analyzed
What it is
Input picks which class or method the application loads.
How it is reached
An attacker can exploit it over the network, with an administrator account, and nobody has to click anything.
What an attacker gains
A successful attack can read the data it protects, change data or behaviour and take it offline. In practice, this kind of flaw lets an attacker run commands or code with the privileges of the affected service. The damage can spread past the vulnerable component into others.
Is it being exploited?
CISA added it to the Known Exploited Vulnerabilities catalog on 2026-08-31: it is being exploited in the wild. EPSS estimates a 63% chance of exploitation activity in the next 30 days, higher than 99% of scored CVEs.
What to do
- Treat it as urgent: it is on CISA's KEV list. CISA's deadline for US federal agencies: 2026-09-14.
- Upgrade PaperCut NG/MF to a fixed version for your release line (24.1.10, 25.0.13, 26.0.5). The patch notes are linked below.
- Until it is patched, review who holds accounts that can reach it.
- Check exposed instances for signs of compromise, not only for the version.
Description from NVD
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.
What this means for your architecture.
A CVE names a product. Whether it matters depends on where that product sits in your systems: what reaches it, which trust boundary it guards and what it can reach once compromised. Veriom maps your components, their relationships and your trust boundaries from your code, cloud and delivery evidence, so you can see where a component like this sits. The radar itself does not look at your systems.
Components it touches
- Application servers and the hosts they run on. The flaw sits between untrusted input and code or command execution.
- Template engines. The flaw sits between untrusted input and code or command execution.
Trust boundaries in play
- Authenticated network access. An account is needed, so exposure follows who can sign in: customers, partners or staff.
- Isolation between components. The impact crosses out of the vulnerable component into others it should be isolated from.
- Between untrusted input and code or command execution. An attacker who crosses it can run commands or code with the privileges of the affected service.
Questions to answer about your own systems
- Where does PaperCut NG/MF run in your systems, and at which version?
- Which of those instances can be reached from the internet or partner networks?
- What can it reach once compromised: which data stores, secrets and services?
Sources
- CVE records and CVSS scores from the NVD CVE API. This product uses the NVD API but is not endorsed or certified by the NVD.
- Exploitation status from CISA’s Known Exploited Vulnerabilities catalog.
- Exploit likelihood from FIRST’s Exploit Prediction Scoring System (EPSS), refreshed daily.
- Explanations are written by Veriom from fixed templates over each record’s data, not by a person reviewing each CVE. Descriptions are quoted from the records as published.