CVE-2024-40711

Veeam Backup & Replication contains a deserialization of untrusted data flaw (CWE-502) that allows an unauthenticated attacker to send a maliciously crafted serialized payload to the product's network-facing service and achieve remote code execution, with no privileges or user interaction required (CVSS 3.1: 9.8). Successful exploitation yields full code execution on the backup server with high impact on confidentiality, integrity and availability, and is especially valuable to attackers because backup infrastructure typically stores credentials and ransomware operators seek to destroy or encrypt backups before attacking production systems. Any organization running Veeam Backup & Replication is in scope; the provided data does not specify exact affected version ranges, so consult Veeam's advisory for the affected/fixed builds. Exploitation is confirmed in the wild: the flaw was added to CISA's KEV on 2024-10-17 with known ransomware use, a public proof-of-concept has been published by watchTowr, EPSS estimates a 90.4% probability of exploitation within 30 days (100th percentile), and the exploit has been reused in Frag ransomware attacks.

What to do: Apply Veeam's security updates immediately (the vendor released fixes for 18 flaws, including 5 critical ones); per the KEV required action, apply mitigations per Veeam's instructions or discontinue use if mitigations are unavailable. Until patched, restrict network access to the backup server from untrusted networks and remove unnecessary internet exposure. Given confirmed ransomware exploitation, also hunt for signs of compromise on backup servers and review backup job integrity and stored credentials.