PaperCut NG/MF Critical Zero-Day Exploited in the Wild
PaperCut confirms active exploitation of critical zero-days CVE-2026-81578 and CVE-2026-82078 in PaperCut NG/MF print management software, with confirmed customer incidents.
PaperCut Software issued an urgent advisory on August 27, 2026, confirming it is investigating active exploitation of flaws in PaperCut NG and PaperCut MF and treating the issue as a security emergency. On August 28 the vendor assigned CVE-2026-81578 and CVE-2026-82078 to the two vulnerabilities forming the exploit chain. At initial disclosure, no CVSS score, vulnerability class, authentication requirements, or exploit path details were public. Rapid7 is tracking the issue as an emerging threat.
- Active exploitation confirmed with customer incidents
- Two CVEs assigned to the exploit chain on Aug 28
- Technical details initially undisclosed by vendor
- Vendor treating issue as a security emergency
Vulnerabilities mentionedAll →
| CVE | Vulnerability | CVSS | EPSS | Flags | Affected | Exposure | Published |
|---|---|---|---|---|---|---|---|
| CVE-2026-82078 +1 in the same advisory: …81578 | Unsafe Reflection RCE in PaperCut NG/MF, Chained with Auth Bypass in Attacks CVE-2026-82078 is an unsafe dynamic class loading flaw (unsafe reflection, CWE-470) in the database connection utilities of PaperCut NG and PaperCut MF: the software instantiates a database driver class based on a configurable driver name without validating it against an allowlist of approved drivers. An attacker who can manipulate system configuration parameters can point that setting at classes of their choosing, causing the server to execute arbitrary Java bytecode residing on the application classpath in the security context of the PaperCut server process. On its own the issue is rated 9.4 (Critical) with high privileges required, but when chained with the companion authentication bypass CVE-2026-81578 it yields unauthenticated remote code execution on the print-management server. All PaperCut NG and MF deployments are in scope; affected version ranges were not specified in the available data, so administrators should consult PaperCut's advisory for fixed versions. The flaw is confirmed exploited in the wild as a zero-day: it was added to CISA's KEV catalog on 2026-08-31, and public reporting describes an AI-orchestrated campaign that compromised PaperCut servers at roughly 395 organizations (~440 servers), with EPSS currently at 1.7% (76th percentile). Do: Upgrade PaperCut NG and MF to the patched release specified in PaperCut's security advisory (exact fixed versions were not provided in this data), prioritizing internet-exposed print servers; the KEV listing means agencies must remediate per CISA BOD 26-04 or discontinue/mitigate per its cloud-service guidance. Restrict the PaperCut web interface from direct internet exposure (VPN/allowlist), review administrator accounts and database driver configuration for tampering, and hunt for post-exploitation activity, since this flaw is being actively chained with the authentication bypass CVE-2026-81578. | 9.4 group max | 2% | KEV |
| mass≈100,000+ organizations / plausibly millions of end users (vendor-cited install base); tens of thousands of on-prem servers with a smaller but significant… |
Overview On August 27, 2026, PaperCut Software published an urgent security advisory stating that it is investigating active exploitation of a vulnerability affecting PaperCut NG and PaperCut MF. PaperCut has confirmed customer incidents and is treating the issue as a security emergency. At the initial time of disclosure, the vulnerability had not been assigned a CVE identifier, and PaperCut had not publicly disclosed a CVSS score, vulnerability class, authentication requirements, or the technical details of the exploit path. However on August 28, the vendor assigned CVE-2026-81578 and CVE-2026-82078 for the two vulnerabilities that make up the exploit chain. CVE…
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