CVE-2025-10035

CVE-2025-10035 is a critical (CVSS 9.8) deserialization-of-untrusted-data flaw (CWE-502) in the License Servlet of Fortra GoAnywhere Managed File Transfer (MFT). It is triggered when the servlet processes a license response carrying a validly forged signature, causing it to deserialize an arbitrary attacker-controlled object; the CVSS vector indicates the attack is network-based and requires no privileges or user interaction. Successful exploitation can lead to command injection (CWE-77), effectively giving an attacker command execution on the MFT server and access to the files and credentials that flow through it. Any organization running GoAnywhere MFT, which is commonly deployed as a central file-transfer hub, is affected, although specific affected/fixed version ranges are not provided in the available data. Exploitation is confirmed in the wild: the flaw was added to CISA's KEV catalog on 2025-09-29 with known ransomware use, Microsoft attributes attacks to the Storm-1175 ransomware affiliate (Medusa, now reportedly replaced by StormEncryptor), and EPSS assigns a 99.8% probability of exploitation within 30 days.

What to do: Apply mitigations or patches per Fortra's vendor instructions immediately, as this is a KEV entry carrying BOD 22-01 requirements for federal agencies (patch or discontinue use if mitigations are unavailable). Because a ransomware affiliate (Storm-1175, using Medusa/StormEncryptor) is actively exploiting it, hunt for compromise: review License Servlet traffic and logs for forged license responses, check for unexpected processes or new accounts, and look for signs of lateral movement. Until patched, restrict or remove internet exposure of GoAnywhere MFT admin and license interfaces.