An attacker exploited a previously unknown and unpatched Cisco vulnerability earlier this year to infiltrate a communications service provider and gain the highest level of access possible, Mandiant said Wednesday.

Cisco has since patched the flaw, one of seven actively exploited zero-day vulnerabilities this year in its SD-WAN (software-defined wide area network) software used to manage internet traffic within organizations, typically those that are widely distributed, such as banks with numerous branches.

But Google-owned cybersecurity firm Mandiant said the attacker (or attackers) could have used its root-level access to obtain broad and undetected visibility into the internal traffic throughout the provider’s entire corporate network. In a caveat, Mandiant also said it could not fully assess how far the compromise actually went because of how cleverly the perpetrators hid their activity.

The attack illustrated hackers’ ongoing targeting of edge devices, Mandiant said. Attacks on such devices have been very common and involved in some of the most consequential breaches in recent years, prompting the Cybersecurity and Infrastructure Agency to direct federal agencies to give them special attention this year.

“This campaign underscores the living off the edge paradigm, where threat actors prioritize the compromise of network appliances to bypass traditional security perimeters,” Mandiant wrote in a blog post. “As organizations increasingly adopt software-defined networking, the orchestrators managing these environments become primary targets. These devices offer a black box environment for threat actors: they often lack the telemetry required for deep forensic analysis, and their role as a central control plane provides a stealthy platform for persistent, wide-scale access to internal enterprise traffic.”

Mandiant didn’t attribute the attack to any specific group, citing the work the attacker did to cover their tracks and delete evidence. But it noted that “for state-sponsored actors, the ability to exploit zero-day vulnerabilities in these platforms remains a premier vector for long-term strategic intelligence collection.”

Kelli Vanderlee, senior manager for Google Threat Intelligence Group, told CyberScoop that “exploiting zero day vulnerabilities in edge devices and the extensive anti-forensic activities are consistent with previously documented cyber espionage threat actor behavior.”

The company also didn’t name the victim service provider.

The attacks on the service provider came in two waves. The first activity Mandiant observed from late 2025 to early 2026 exploited one of two then-unpatched vulnerabilities (CVE-2026-20127 or CVE-2026-20182), with the attacker making unauthorized “peering” connections to the victim’s SD-WAN Manager devices in a kind of digital handshake to verify identity and trust.

Once there, the attacker facilitated its access and used it to manipulate default account passwords in hopes of avoiding detection. Next, the attacker exploited the zero-day vulnerability (CVE-2026-20245) in Cisco Catalyst SD-WAN Manager, activity Mandiant observed in March, and created a rogue user account, “troot” that gave full root-level control.

“On June 4, 2026, Cisco published a security advisory about a privilege escalation vulnerability in Cisco Catalyst SD-WAN Manager,” a Cisco spokesperson said. “Cisco strongly recommends customers upgrade to a fixed software release as outlined in the advisory.”

Updated 6/24/26: to include Cisco comment.

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Researchers are warning that cybercriminals exploited an Oracle PeopleSoft zero-day vulnerability and potentially infiltrated the networks of more than 100 organizations in an attack spree that largely impacted higher education.

Mandiant and Google Threat Intelligence Group said it became aware of the attacks earlier this month as part of its ongoing monitoring of ShinyHunters operations. The notorious cybercrime group claims it hacked more than 100 organizations and started naming victims and publishing allegedly stolen data Tuesday.

University of Nottingham, one of ShinyHunters’ alleged victims, on Wednesday confirmed a significant amount of student data was stolen during a cyberattack after the threat group leaked some of the school’s data.

The attacks date back to at least May 27, according to Mandiant, and involve the exploitation of CVE-2026-35273, a defect in Oracle PeopleSoft PeopleTools that allows unauthenticated attackers to execute remote code and takeover affected servers.

Oracle disclosed the vulnerability and recommended some steps for mitigation Wednesday, weeks after the attacks were already underway. The vendor hasn’t released a patch to address the defect and did not respond to a request for comment.

Google said it alerted more than 100 organizations of potentially vulnerable endpoints in their environments, but it declined to confirm how many victims are compromised. 

“This campaign is still active. We have observed ShinyHunters sending extortions as recently as today,” Charles Carmakal, chief technology officer at Mandiant Consulting, told CyberScoop Thursday evening. He added that more victims, beyond Google’s visibility, may be impacted.

Most of the potential victim pool is based in the United States and 68% are in the higher education sector, according to Google.

“We have previously observed ShinyHunters target the education sector this year, however it’s possible this targeting is representative of the majority of exposed PeopleSoft instances belonging to the sector,” Carmakal said. 

Oracle PeopleSoft PeopleTools includes more than 40 tools for human resources and customer relationship management.

The attacks come less than a year after the Clop ransomware group exploited a zero-day in Oracle E-Business Suite that affected dozens of victims. The data theft extortion campaign that followed those attacks, which began in August, didn’t get underway until October.

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