Threat actors have been observed exploiting a recently disclosed critical security flaw in SonicWall Secure Mobile Access (SMA) 1000 appliances within days of public disclosure.
The vulnerability, tracked as CVE-2026-102255 (CVSS score: 10.0), is a case of pre-authenticated server-side request forgery (SSRF) that could allow a remote attacker "to direct the appliance to issue requests on their behalf and reach internal functionality and perform unauthorized operations."
Patches for the flaw were released by SonicWall on October 6, 2026, with versions 12.4.3-03670 (platform-hotfix) and 12.5.0-03082 (platform-hotfix).
The vulnerability has since started witnessing active exploitation attempts, with first signs detected by threat intelligence firms Defused Cyber and Previdian on October 8, 2026.
Data from Previdian shows that a total of 135 attempts have been observed to date from two unique IP addresses located in the U.S. SonicWall has yet to update the advisory to reflect active exploitation of the flaw.
CVE-2026-102255 is the latest vulnerability impacting SonicWall SMA 1000 appliances to come under active exploitation. In June 2026, two other flaws in the same product (CVE-2026-15409, CVSS score: 10.0, and CVE-2026-15410, CVSS score: 7.2) were weaponized as zero-days by a threat actor dubbed UTA0533 to deploy Java web shells and a malware called KNUCKLEBALL.
Rapid7 also said it observed threat actors leveraging the flaws to target internet-facing devices and use them as a stealthy initial access vector to execute commands on the operating system and ensure long-term, persistent access.
"Once they established a foothold on the appliance, the actors systematically extracted high-value credentials, active session databases, and Time-Based One-Time Password (TOTP) multi-factor authentication (MFA) seed configurations," the company noted.
"With these harvested resources, the threat actors quickly shifted to lateral movement, pivoting from the compromised appliance directly into the internal corporate network."
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