Attackers are exploiting two new PaperCut flaws to steal credentials and gain privileged access in education-sector attacks across the U.S. and Europe.

Attackers are exploiting two recelty disclosed PaperCut flaws, CVE-2026-81578 and CVE-2026-82078, in attacks targeting schools and other education organizations in the U.S. and Europe, as reported by TheHackerNews.

Arctic Wolf researchers observed threat actors chaining an authentication bypass with remote code execution to run commands, perform reconnaissance and create privileged accounts. The activity shows how quickly attackers can turn newly disclosed vulnerabilities into real-world attacks, putting sensitive credentials and systems at risk.

“Arctic Wolf observed exploitation of PaperCut servers affected by CVE-2026-81578 and CVE-2026-82078 leading to command execution, reconnaissance, and attempts to create privileged accounts.” reads the advisory. “Observed post-exploitation activity included delivery of Windows registry hive collection tools, Metasploit/Meterpreter-related Java payloads, and commands used to identify hosts, users, processes, and sensitive configuration data.”

PaperCut, an enterprise print-management platform, has a history of exploitation, including attacks that delivered LockBit ransomware. PaperCut disclosed active exploitation of the latest flaws on August 27, 2026. CISA added both to its Known Exploited Vulnerabilities catalog on August 31.

Attackers used PaperCut flaws to run basic system checks, create a privileged account named Administrator17, and collect system and user data.

They downloaded credential-harvesting tools with certutil and used Meterpreter Java payloads to establish remote sessions. The attackers also searched PaperCut configuration files for passwords, secrets, LDAP settings and tokens.

Researchers observed lsa_collect.exe extracting registry keys to recover the Windows BootKey, which could give attackers access to the SAM database and stored credentials.

Defenders should review PaperCut server.log files for known exploitation indicators and look for unusual five-character .class, .cmd, or .out files. Monitor pc-app.exe for command shells such as cmd.exe and powershell.exe, and investigate commands like whoami, tasklist, ver, and uname.

Also check for credential-harvesting tools, unexpected privileged accounts such as Administrator17, suspicious requests to /custom/pcp_*.txt, and large downloads using python-requests.

Finally, keep PaperCut management interfaces off the public internet and install the vendor’s security fixes.

Follow me on Twitter: @securityaffairs and Facebook and Mastodon

Pierluigi Paganini

(SecurityAffairs – hacking, PaperCut)

U.S. Cybersecurity and Infrastructure Security Agency (CISA) adds PaperCut NG/MF flaws to its Known Exploited Vulnerabilities catalog.

The U.S. Cybersecurity and Infrastructure Security Agency (CISA) added the following vulnerabilities to its Known Exploited Vulnerabilities (KEV) catalog:

• CVE-2026-81578 (CVSS score of 8.8) PaperCut NG/MF Missing Authentication for Critical Function Vulnerability 
• CVE-2026-82078 (CVSS score of 9.4) PaperCut NG/MF Unsafe Reflection Vulnerability 

PaperCut, the print management software running in schools, hospitals, and offices worldwide, recently confirmed that a pre-authentication remote code execution flaw, tracked as CVE-2026-81578, is being actively exploited against real customers. Researchers at Huntress found evidence of exploitation in two customer environments, and the security firm went further, reproducing the entire attack chain from scratch against a clean, unpatched install.

“Observed activity focused on system discovery. We have not observed secondary malware, further command-and-control traffic, or additional persistence or post-exploitation from the recovered payload.” reads the report published by Hutress.

“Huntress reproduced a full pre-authentication RCE chain against a vanilla PaperCut NG 25.0.11.75758 server. We have reached out to PaperCut to coordinate with them on continued vulnerability analysis.”

The vulnerability starts with a simple authorization mistake in PaperCut. An attacker can send a specially crafted request that makes the server display one page while actually running an action from another page.

PaperCut checks the permissions for the page it displays instead of the action it actually performs. The flaw CVE-2026-81578 can let an attacker change the server’s configuration without logging in.

That access can then be combined with a second flaw, CVE-2026-82078. The issue in PaperCut’s database utilities can load unsafe Java classes, allowing the attacker to run arbitrary Java code on the server.

The real-world attacks Huntress observed were almost quaint compared to the severity of the bug itself. One incident lasted under two minutes total, with the attacker running nothing more aggressive than whoami and ver, basic commands to identify the compromised account and Windows version. A second incident added tasklist to the mix, checking what processes were running, but neither case showed evidence of deeper persistence, secondary malware, or follow-up command-and-control traffic.

The activities observed by Huntress read like reconnaissance rather than a finished operation, the kind of activity that usually precedes something worse.

The forensic trail attackers left behind is genuinely useful for defenders, and it’s worth understanding exactly what it looks like. Investigators found a malicious Java class file dropped directly into PaperCut’s own installation directory, capable of running commands, writing results to a temporary file, and then deleting both the output and the server’s own log file to cover its tracks. One artifact survived that cleanup regardless: a Derby database log entry reading memory:...\pwn, an oddly named database directory that PaperCut’s own investigation guidance now flags as a high-confidence indicator of compromise.

“After exploitation, the .class file deletes its own Udydn.out file, as well as the server’s server.log file. The server.log file recorded the execution of this code in a log line that contains the string DB URL: jdbc:derby:memory:pwn that immediately followed the large encoded data blob’s appearance in the log.” continues the report. “We observed /data/internal/derby.log was not deleted, and it contains one insightful breadcrumb”

PaperCut’s patching process is more complicated than simply installing an update. The company released an emergency patch first, then issued another update less than 24 hours later after additional testing. Fixes for version 24 were still being developed when the report was published.

The timing is important because the second confirmed attack targeted a server running version 24, before the fix for that version was available.

Huntress successfully recreated the exploit chain in a test environment. From a remote system, the researchers were able to trigger code execution without authentication. The attack caused PaperCut’s pc-app.exe Application Server to launch charmap.exe with SYSTEM privileges, confirming that the vulnerability can lead to code execution at the highest Windows privilege level.

The bigger concern involves older versions. Huntress found that about 47% of the roughly 2,500 PaperCut installations it tracks still run version 23 or earlier, and there is currently no patch for those versions.

According to Binding Operational Directive (BOD) 22-01: Reducing the Significant Risk of Known Exploited Vulnerabilities, FCEB agencies have to address the identified vulnerabilities by the due date to protect their networks against attacks exploiting the flaws in the catalog.

Experts also recommend that private organizations review the Catalog and address the vulnerabilities in their infrastructure.

CISA orders federal agencies to fix the flaws by September 14.

Follow me on Twitter: @securityaffairs and Facebook and Mastodon

Pierluigi Paganini

(SecurityAffairs – hacking, CISA)

PaperCut vulnerability CVE-2026-82078 is exploited in the wild. Attackers run malicious SQL for RCE and a Metasploit PoC is public. Patch now.

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The post CVE-2026-81578 & CVE-2026-82078: PaperCut Zero-Day Exploited, PoC Public appeared first on Daily CyberSecurity.

PaperCut confirms a NG/MF vulnerability exploited in the wild. Restrict server access now and apply the emergency patch for versions 25 and 26.

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The post PaperCut NG/MF Vulnerability Exploited in the Wild, Emergency Patch Released appeared first on Daily CyberSecurity.