Unpatched AhsayCBS Vulnerabilities Exploited in the Wild

Hackers have been exploiting two unpatched vulnerabilities in the AhsayCBS backup solution for remote code execution (RCE), cybersecurity firm Huntress warns.

A centralized cloud backup server management console developed by Ahsay Systems, AhsayCBS provides backup policy, storage, and user management and is popular among MSPs and system integrators.

Tracked as CVE-2026-105133 and CVE-2026-105134, the exploited security defects allow attackers to manipulate arguments in certain functions of the tool to bypass authentication and inject OS commands.

They were disclosed on October 4, when NIST warned that exploit code targeting them had been released, and that all AhsayCBS versions up to 10.3.2 were affected.

On Thursday, Huntress warned that attackers have exploited the two flaws in the wild and that the latest AhsayCBS version, 10.3.4, is also affected.

“Until a patch is available, we recommend restricting access to the management interface and investigating for signs of compromise,” Huntress says.

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According to Huntress, threat actors are chaining the two bugs to access vulnerable systems and execute arbitrary code on them. As of October 8, at least five organizations had been targeted.

“Huntress observed threat actors exploiting the vulnerabilities to gain unauthenticated remote code execution and deploy webshells on exposed systems,” the cybersecurity firm notes.

It also warns that CVE-2026-105134 can be exploited for unauthenticated RCE with System privileges through an API of the Replication Receiver component.

“The API contains an authentication bypass that could allow for a random token to substitute valid credentials. After exploitation, a threat actor configured a malicious receiver and dropped a Java Server Page (JSP) webshell into the application directory served by the CBS application,” Huntress explains.

After gaining initial access, the attackers conducted reconnaissance and deployed XMRig cryptominers disguised as Microsoft Edge. They also planted an AI-assisted PowerShell script to monitor Task Manager and terminate it if it remains open for too long.

They also achieved persistence by creating a Windows service masquerading as Microsoft Edge Update to execute a modified copy of the legitimate NSSM utility named msedge.exe with System privileges.

“NSSM can support other programs to ensure they stay running and restart after a crash or reboot, and threat actors in this incident likely used it to maintain persistence for edge.exe, while disguising the service-related binary as a legitimate-looking file,” Huntress notes.

In one attack, the hackers deployed WinRing0x64.sys, a legitimate but vulnerable kernel driver that enabled the cryptocurrency miner to operate with kernel-level access.

“Organizations should restrict AhsayCBS management interface web access, as the exploit targets the externally accessible web app service on the host. Access should be limited to trusted IP addresses only or require VPN,” Huntress recommends.

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