🟠 High | Source: Microsoft Security Response Center
CVE-2018-5407, also known as PortSmash, is a hardware-level side-channel vulnerability affecting processors that use Simultaneous Multi-threading (SMT), such as Intel Hyper-Threading. It allows a local attacker running a malicious process on the same physical CPU core to steal sensitive data — such as cryptographic keys — from another process by measuring timing differences in how execution ports are used. In shared cloud environments, this is particularly concerning as co-located workloads share physical hardware.
Security Architect’s Take: Review whether SMT/Hyper-Threading is enabled on Azure VMs handling sensitive cryptographic operations; consider using dedicated hosts or disabling Hyper-Threading on instances processing high-value secrets. Ensure OpenSSL and other cryptographic libraries are patched to versions that include PortSmash mitigations, and evaluate whether tenant isolation guarantees on shared infrastructure are sufficient for your threat model.