# Four-byte write plus timing bug lets researchers run code in Windows SmartScreen enclave

Researchers found that combining a four-byte memory write with a timing bug let them execute their own code inside the isolated enclave Windows SmartScreen uses to vet files and downloads. Because that enclave is a key security boundary designed to stay tamper-resistant, code execution there could undermine the protection it provides to Windows users. The finding matters for defenders and Microsoft alike, as it shows the weakness of assuming hardware-backed enclaves are inherently safe.

**Importance:** 4/5

## Sources

### Security
- [The Hacker News](https://thehackernews.com/2026/10/four-byte-write-and-timing-bug-let.html) — Wed, 14 Oct 2026 11:22:28 +0530