Threat actor

Clop

0 mentions in 7 days · 4 in 30 days · 4 total · first seen Aug 19, 2026 · last 15d ago

Timeline4 articles

PaperCut NG/MF vulnerabilities exploited in zero-day attacks

PaperCut warns of active zero-day exploitation chaining CVE-2026-81578 and CVE-2026-82078 for pre-auth remote code execution in NG/MF print management.

PaperCut Software confirmed attackers are chaining two vulnerabilities in PaperCut NG and MF: CVE-2026-81578, an improper access control flaw in the web management interface allowing unauthenticated configuration changes, and CVE-2026-82078, unsafe dynamic class loading in database connection utilities enabling arbitrary Java bytecode execution. Huntress reproduced a pre-authentication remote configuration takeover and full RCE chain against PaperCut NG 25.0.11.75758 and observed limited exploitation at two customers, including post-exploitation whoami and ver commands. The vendor released Emergency Patch Release 2 with additional hardening and urged restricting Application Server web access to trusted IPs. In 2023, Clop and LockBit affiliates abused CVE-2023-27350 and CVE-2023-27351 in the same software.

Help Net SecurityAug 31, 14:39 UTC · 15d agoExploit / PoC in the wildCVE-2026-81578 CVE-2026-82078 CVE-2023-27350+1 CVEs

PaperCut warns of hackers using printer management software flaw in attacks

PaperCut warns of active exploitation of CVE-2026-82078 and CVE-2026-81578 in NG/MF print management software used by universities, corporations, and governments.

PaperCut issued an emergency advisory saying vulnerabilities in PaperCut NG and MF, tracked as CVE-2026-82078 and CVE-2026-81578 with severity scores above 8.8, are under active exploitation with confirmed customer incidents. Huntress reported at least two customers impacted, and an initial patch was revised with input from Huntress and watchTowr researchers. PaperCut software is widely deployed at universities, corporations, and governments managing printers from Canon, Epson, Xerox, and Brother, and the vendor urged removing server web interfaces from the public internet. Previous PaperCut flaws were used by ransomware gangs like Bl00dy and Clop, and CISA has warned the education sector is particularly exposed.

The RecordAug 28, 16:37 UTC · 18d agoExploit / PoC in the wildCVE-2026-82078 CVE-2026-81578

Clop-Linked Windchill Web Shell Decrypts Credentials and Maps Engineering Data

ReliaQuest details a bespoke JSP web shell that Clop deploys on hacked PTC Windchill and FlexPLM servers after exploiting CVE-2026-12569.

ReliaQuest analyzed a custom Java web shell planted on vulnerable PTC Windchill and FlexPLM servers following exploitation of CVE-2026-12569 (CVSS 9.3). The implant decrypts Windchill keystore credentials including the LDAP manager password, enumerates the file vault for engineering data, and loads attacker-supplied Java classes in memory for post-exploitation. Commands let operators read and delete files, exfiltrate results, and deliver follow-on payloads such as ransomware. Ransom-ISAC, eCrime.ch and Defused previously attributed the campaign to the Clop data-theft extortion group.

The Hacker NewsAug 19, 15:27 UTC · 27d agoThreat actor in the wildCVE-2026-12569

The long tail of Clop’s PTC hack is just beginning to emerge

Clop mass-exploited CVE-2026-12569 in PTC Windchill and FlexPLM in early June, claiming data theft from dozens of large organizations.

Clop began sending extortion emails in mid-July after exploiting CVE-2026-12569 in PTC Windchill and FlexPLM, likely as a zero-day in early June before PTC's June 17 disclosure and patch. Confirmed victims include Toast and Zebra, while GE, Philips and Shell are among claimed victims. CISA added the flaw, which allows unauthenticated remote code execution, to its KEV catalog on June 25. ReliaQuest said the group used a custom Windchill-specific web shell for credential theft and large-scale exfiltration, echoing its past MOVEit and Oracle E-Business Suite mass-exploitation campaigns.

CyberScoopAug 19, 14:30 UTC · 27d agoThreat actor in the wildCVE-2026-125691

Related CVEsby mentions

CVE-2026-820789.42%
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).
· PaperCut NG · PaperCut MF KEVmass
CVE-2026-125699.341%
Unauthenticated RCE in PTC Windchill and FlexPLM
PTC Windchill and FlexPLM contain an improper input validation flaw (CWE-20) with an associated deserialization of untrusted data weakness (CWE-502) that allows an unauthenticated, remote attacker to execute arbitrary code by sending a malicious request over the network. An attacker who can reach a vulnerable Windchill or FlexPLM server can run arbitrary code on it, potentially gaining a foothold for lateral movement; CISA notes the flaw is being used in ransomware campaigns. All organizations running PTC Windchill or FlexPLM are affected, and the available data does not specify affected version ranges. The vulnerability was added to CISA's Known Exploited Vulnerabilities catalog on 2026-06-25 with known ransomware use, and EPSS assigns a 40.6% probability of exploitation within 30 days (99th percentile). No CVSS score or public proof-of-concept is available yet, but the KEV listing confirms exploitation in the wild.
· PTC Windchill · PTC FlexPLM KEV ransomwaremoderate
CVE-2026-815788.82%
Missing Authentication for Critical Function in PaperCut NG/MF Web Interface
CVE-2026-81578 is an improper access control flaw (CWE-305) in the web management interface of PaperCut MF and PaperCut NG in which administrative requests from unauthenticated remote users trigger backend actions before access validation completes. An attacker can invoke administrative functions without logging in, allowing modification of certain system configurations. When chained with CVE-2026-82078 (unsafe dynamic class loading), the flaw has been used to achieve unauthenticated code execution. Any organization running PaperCut NG/MF, particularly servers whose web management interface is reachable from the internet or untrusted networks, is affected. The vulnerability was added to CISA KEV on 2026-08-31 and is being exploited in the wild as part of an AI-orchestrated campaign that compromised roughly 395–440 organizations.
· PaperCut MF · PaperCut NG KEVlarge
CVE-2023-273509.8100%
Authentication Bypass Leading to SYSTEM RCE in PaperCut MF/NG
PaperCut MF and PaperCut NG print management software contain an improper access control flaw (CWE-284) in the SetupCompleted class that allows an unauthenticated attacker to bypass authentication and reach internal administrative functionality. The flaw is triggered by sending crafted, unauthenticated requests to the PaperCut application's web interface, without requiring valid user credentials. A successful attacker gains the ability to execute code in the context of the SYSTEM account on the PaperCut server, typically a Windows print server, giving full control of that host. Any organization running PaperCut MF or NG is potentially affected, and exposure is highest where the server's web interface is reachable from the internet or by untrusted networks. Exploitation is confirmed in the wild: CISA added the flaw to the KEV on 2023-04-21 with known ransomware use, and EPSS rates exploitation probability at 100% within 30 days.
· PaperCut MF · PaperCut NG KEV ransomware PoC ×3mass
CVE-2023-273517.578%
Authentication Bypass in PaperCut NG/MF Print Management Software
CVE-2023-27351 is an improper authentication flaw (CWE-287) in the SecurityRequestFilter class of PaperCut NG and MF print management software, where the authentication algorithm is improperly implemented. A remote, unauthenticated attacker can trigger it over the network with no user interaction or special privileges to bypass authentication on the affected server (CVSS 3.1: 7.5). Once authentication is bypassed, the attacker gains access to the PaperCut system; in observed campaigns this access was leveraged to deliver Cl0p and LockBit ransomware, as confirmed by Microsoft. Organizations running PaperCut NG (version 22.0.5, Build 63914, is cited in the advisory) or PaperCut MF are affected. The flaw was exploited as a zero-day, is CISA KEV-listed (added 2026-04-20) with known ransomware use, and EPSS places the 30-day exploitation probability at 78.1%.
· PaperCut NG 22.0.5 (Build 63914) explicitly cited as affected; CISA lists PaperCut NG broadly without a full version range · PaperCut MF affected per CISA listing; no specific version range provided in the data KEV ransomwarelarge

Appears with

vendor PTC 2 vendor watchTowr 2 product PaperCut MF 2 product PaperCut NG 2 organization Ransom-ISAC 2 product FlexPLM 2 vendor Huntress 2 organization CISA 2 organization ReliaQuest 2 product MOVEit 1 product Oracle E-Business Suite 1 product PTC Windchill 1 product Windchill 1 vendor PaperCut 1 vendor PaperCut Software 1 victim GE 1

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