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VU#687587: AOMEI Backupper amwrtdrv.sys local privilege escalation vulnerability allows arbitrary writes to physical disks

AOMEI Backupper 8.4.0 driver flaw CVE-2026-12780 lets unprivileged users write physical disks and execute UEFI code, bypassing HVCI and EDR.

CERT/CC issued VU#687587 for CVE-2026-12780, an incorrect permission assignment (CWE-732) in the amwrtdrv.sys kernel driver shipped with AOMEI Backupper 8.4.0. The driver exposes a world-accessible device object without a security descriptor, allowing any unprivileged user to write arbitrary physical disk sectors; with Secure Boot disabled, an attacker can modify the GPT and inject a UEFI payload that executes before the OS loads, bypassing HVCI, EDR, Windows Defender and Hyper-V isolation. On TPM-only BitLocker configurations the attack can capture Volume Master Key material during pre-boot. AOMEI has shipped patches; users who cannot update should uninstall the software or disable the amwrtdrv.sys service, and enabling Secure Boot adds defense in depth.

GNU GRUB 2.14: serial-MMIO lockdown bypass in Canonical-signed gcdx64.efi

Canonical-signed GRUB2 serial command accepts arbitrary MMIO addresses, letting local attackers with grub.cfg control bypass Secure Boot lockdown.

A vulnerability in Canonical's grub-efi-amd64-signed (gcdx64.efi, GRUB 2.14) exposes a serial command that accepts a caller-supplied 64-bit MMIO base address. The lockdown path does not restrict this command even when lockdown=y under UEFI Secure Boot, and the serial implementation does not validate that the requested register span belongs to a real UART rather than ordinary RAM. A local attacker with control of GRUB's boot configuration can abuse this to bypass the Secure Boot lockdown.

oss-security · 3d agoVulnerability2

Windows 11’s strongest security defenses can be bypassed without a screwdriver

Researchers found a script-only attack, 'Download More RAM', that rewrites DIMM configuration chips to bypass Windows 11 VBS and HVCI security boundaries.

Researchers at the University of Birmingham and Durham University showed that overwriting configuration data on unprotected DDR4/DDR5 module chips creates memory aliases that let attackers with existing privileged access defeat Virtualisation-based Security and HVCI, re-enable blocklisted drivers, kill EDR, and bypass group policy. Microsoft assigned CVE-2026-23670 and shipped mitigations in its April 2026 updates; systems with Secure Boot enabled are protected. Affected unprotected product lines are estimated at more than half of the high-performance consumer memory market and over 70% of the gaming segment.

Help Net Security · Aug 17, 2026VulnerabilityCVE-2026-236701