Critical Vulnerabilities in PaperCut NG and PaperCut MF Exploited in the Wild
PaperCut Software has released urgent patches for two critical vulnerabilities affecting its printing management products PaperCut NG and PaperCut MF. The flaws were publicly disclosed on August 27, 2026, and active exploitation has already been observed in customer environments.
The first vulnerability, tracked as CVE-2026-81578, arises from insufficient access controls in the web management interface. Under specific conditions, an attacker can execute backend management functions without authentication, enabling remote modification of certain system settings.
The second issue, CVE-2026-82078, involves unsafe dynamic class loading during database connection handling. When an attacker can manipulate system settings via the first flaw, they can load and execute arbitrary Java bytecode under the privileges of the PaperCut server process.
According to CVSS v4.0 scoring, CVE-2026-82078 received a base score of 9.4 (Critical) while CVE-2026-81578 scored 8.8 (High). PaperCut Software strongly recommends immediate application of the emergency patches.
The vulnerabilities have also been added to the CISA Known Exploited Vulnerabilities Catalog, underscoring the real-world threat they pose to organizations using the affected printing management software.
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