Critical · published August 28, 2026
CVSS calls it critical at 9.1. It is confirmed in active exploitation. It sits in the 99.2th percentile for exploit probability.
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.
| Product | Versions | Fixed in |
|---|---|---|
| papercut/papercut_mf | < 24.1.9 | 24.1.9 |
| papercut/papercut_mf | ≥ 25.0.2, < 25.0.12 | 25.0.12 |
| papercut/papercut_mf | ≥ 26.0.2, < 26.0.4 | 26.0.4 |
| papercut/papercut_ng | < 24.1.9 | 24.1.9 |
| papercut/papercut_ng | ≥ 25.0.2, < 25.0.12 | 25.0.12 |
| papercut/papercut_ng | ≥ 26.0.2, < 26.0.4 | 26.0.4 |