AI-powered attack exploited PaperCut flaws to hack 395 organizations

CVE-2021-42287 is an elevation-of-privilege vulnerability in Microsoft Active Directory Domain Services (AD DS) affecting multiple supported Windows Server releases. An attacker with any low-privileged domain account can trigger it — commonly in combination with the related sAMAccountName spoofing flaw CVE-2021-42278 — by manipulating account name attributes so the Kerberos Key Distribution Center issues tickets that grant rights normally reserved for domain controllers. The result is escalation from a standard user to domain administrator, giving the attacker full control over the Windows domain, a capability that is directly useful for ransomware deployment and data theft. Any organization running Active Directory on the affected Windows Server versions is exposed, which amounts to essentially every enterprise Windows network. The flaw is actively exploited: it was added to CISA's Known Exploited Vulnerabilities catalog on 2022-04-11 with known ransomware use, and EPSS assigns it a 77.2% probability of exploitation within 30 days.

Do: Apply Microsoft's security updates to every domain controller — writable and read-only — as soon as possible (the fix shipped in Microsoft's November 2021 security releases), prioritizing internet-exposed and VPN-facing DCs. Hunt domain controller logs for anomalous Kerberos TGT requests by user accounts with domain-controller-style names (a hallmark of CVE-2021-42278/42287 abuse) and monitor for ransomware staging activity, given documented ransomware use.

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.