A Cl0p ransomware affiliate has been observed exploiting a critical-severity remote code execution (RCE) vulnerability in PTC’s product lifecycle management (PLM) platforms Windchill and FlexPLM.

Tracked as CVE-2026-12569 (CVSS score of 9.3), the security defect is described as a deserialization of untrusted data issue that can be exploited without authentication.

Patched on June 17, the bug was flagged as exploited in the wild the next day, when PTC published indicators of compromise (IoCs). It was added to CISA’s KEV catalog at the end of June.

Fresh warnings from ReliaQuest and Ransom-ISAC (in collaboration with eCrime.ch and Defused) show that the vulnerability is now exploited in the wild by a Cl0p affiliate.

“The actor behind these attacks remains unconfirmed. However, the observed tradecraft shares characteristics with previous Cl0p campaigns targeting enterprise applications and high-value data repositories,” ReliaQuest says.

A detailed Ransom-ISAC advisory shows that the attackers have been chaining a “pre-authentication information disclosure in the FlexPLM WSDL endpoint with a server-side flaw in the Windchill login servlet” to achieve RCE and deploy JSP webshells.

Following initial access, the hackers have been observed enumerating filesystems, staging data, and exfiltrating data for extortion.

Starting July 20, the attackers have been targeting organizations across the aerospace, automotive, manufacturing, and retail/apparel sectors, Ransom-ISAC’s advisory reads.

As part of the observed campaign, the threat actor has been sending extortion emails with a subject line “Windchill PDMLink module serious data leak” to hundreds of users within the impacted organizations.

“As of 22 July, Cl0p ransomware has not begun listing victims of this latest campaign on their dark web data leak site or has publicly claimed credit for this latest campaign,” Ransom-ISAC says.

Organizations are advised to apply PTC’s patches and to use previously published and newly shared IoCs to conduct threat hunting. They should also follow PTC’s remediation steps.

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