SECURITY researchers demonstrated a local, sandbox-bypassable bug inside a Windows protected enclave used by Defender SmartScreen’s Enhanced Phishing Protection. The flaw, tracked as CVE-2026-83498, existed in the SFAPE[.]dll component that runs inside a VBS enclave. By repeatedly calling the enclave’s Initialize function, an attacker could perform an arbitrary four-byte write to a caller-controlled address, bypassing the initial address check.
A subsequent timing bug in another function then allowed a controlled wipe that redirected how the enclave looks up stored objects, enabling read and write access that could corrupt the enclave’s memory boundary checks and potentially allow attacker-chosen code to run inside the enclave. Microsoft describes the practical impact as either data leakage from the enclave or code execution within it, though the proof-of-concept did not demonstrate password exfiltration.
Microsoft released a cumulative update on 8 September 2026 (KB5124008) that patches Windows 11 versions 24H2 and 25H2 and also ships a policy to block the old, vulnerable SFAPE enclave from loading in patched systems. Doyensec’s analysis confirms the patched enclave now checks the address before the initial write and tightens the timing vulnerability.
There remains an open question whether other enclaves with similar flaws, such as a pre-existing Edge enclave linked to CVE-2023-36880, could still load on patched systems, and the researchers note that “bring your own vulnerable enclave” remains a potential workaround for attackers. The vulnerability was disclosed publicly on 13 October 2026 after patch deployment, and there have been no observed targeted exploits in the wild.