CVE-2019-8900

A flaw in the SecureROM (BootROM) of certain Apple devices allows an unauthenticated local attacker to execute arbitrary code when the device boots. Triggering it requires physical access: the attacker must connect the device to a computer and place it in Device Firmware Update (DFU) mode during boot. An attacker gains the ability to run code on the device during that boot session, but the exploit is not persistent — a reboot reverts any software changes — and without the device's unlock PIN or fingerprint the attacker cannot reach data protected by Secure Enclave or Touch ID. Affected are Apple devices with a vulnerable SecureROM; per the source data no specific model list or version range is given, and because BootROM is read-only, vulnerable devices cannot be fully patched by firmware updates. Per available dashboard data there is no known in-the-wild exploitation and no public PoC (not in CISA KEV), although EPSS assigns a 68.8% probability of exploitation within 30 days (99th percentile).

What to do: No firmware update can remediate an immutable BootROM flaw, so treat this as a physical-security issue: avoid leaving devices unattended, and only put devices into DFU mode connected to trusted, up-to-date computers. If untrusted access is suspected, simply rebooting the device clears any non-persistent changes made during the exploited boot session. Keep host computers used for device restores and DFU work patched, and protect unlock credentials, since the PIN/fingerprint gates access to Secure Enclave-protected data.