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Microsoft said some Windows Server 2025 devices may enter BitLocker recovery after installing the April 2026 KB5082063 security update, affecting systems with a specific and discouraged BitLocker Group Policy tied to TPM platform validation, PCR7, and Secure Boot conditions during transition to the 2023-signed Windows Boot Manager. The company said the recovery key prompt should typically appear only on the first restart, is preparing a fix, and advised administrators to remove the problematic policy before deployment or use Known Issue Rollback; the issue is mainly expected in enterprise-managed environments rather than personal devices.
Separately, researchers disclosed BitUnlocker, a downgrade attack that can expose data on BitLocker-protected Windows 11 systems in under five minutes with physical access by exploiting CVE-2025-48804 in the Windows Recovery Environment. The attack works because Secure Boot may still trust older Microsoft Windows PCA 2011-signed boot managers, allowing a pre-patch bootmgfw.efi and modified WinRE chain to launch cmd.exe with the encrypted volume already mounted; systems using TPM-only BitLocker remain at risk unless organizations migrate trust to Windows UEFI CA 2023 via KB5025885 or require TPM+PIN pre-boot authentication.
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6 events from the most recent confirmed update back to the earliest known activity.
Microsoft resolved the April 2026 BitLocker recovery problem for Windows 11 version 25H2 with cumulative update KB5089549. The company said the issue was tied to an unsupported BitLocker Group Policy and noted that fixes for Windows 10 and Windows Server would come in a future update.
A public proof of concept for BitUnlocker was released on GitHub, increasing the urgency for defenders to enable pre-boot authentication, verify boot manager certificates, and migrate away from PCA 2011 trust.
Researchers publicly described BitUnlocker, a downgrade attack that can access BitLocker-protected Windows 11 disks in under five minutes with physical access by abusing CVE-2025-48804 through a trusted older boot manager and modified WinRE chain. They said TPM-only BitLocker systems are vulnerable while TPM+PIN and systems migrated to Windows UEFI CA 2023 are protected.
Microsoft confirmed the Windows Server 2025 BitLocker recovery problem, said the recovery key should typically be needed only on the first restart, and stated it was working on a fix. The company advised admins to remove the relevant Group Policy before deployment or use Known Issue Rollback.
After installing the April 2026 KB5082063 security update, some Windows Server 2025 devices booted into BitLocker recovery. Microsoft said the issue affects systems with a specific unsupported BitLocker Group Policy configuration tied to TPM platform validation and Secure Boot conditions.
Microsoft fixed CVE-2025-48804 in bootmgfw.efi in July 2025, but older Microsoft Windows PCA 2011-signed boot managers remained trusted on affected systems. This left a downgrade path that later enabled the BitUnlocker attack scenario.
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Researchers detailed multiple attack paths that can defeat or weaken Microsoft BitLocker on systems using **TPM-only** unlock, showing that physical access remains enough to recover disk encryption keys or bypass pre-boot protections in common configurations. Neodyme revisited the **Bitpixie** technique tied to `CVE-2023-21563`, describing how attackers can downgrade the Windows Boot Manager, abuse a PXE soft-reboot path, and recover the Volume Master Key from memory without the user’s password. A follow-up analysis said Microsoft has struggled to fully close downgrade paths because Secure Boot revocation capacity is limited, older Microsoft-signed bootloaders remain broadly trusted, and stricter PCR bindings have caused recovery and compatibility problems in the field. Separate research from MDSec showed that Dell UEFI firmware can be modified offline at the SPI flash level to disable pre-boot DMA protections while leaving BIOS settings appearing unchanged, enabling follow-on DMA attacks against Windows 11 devices protected by TPM-only BitLocker and, in some cases, privilege escalation even on TPM+PIN systems when the PIN is known. A public GitHub project compiling BitLocker attack techniques further underscored the breadth of the issue, cataloging hardware and software methods ranging from TPM bus sniffing and fTPM glitching to bootloader, WinRE, and recovery-environment flaws across numerous CVEs. Across the disclosures, the consistent mitigation theme was to avoid relying on TPM-only unlock where possible, apply Microsoft’s Secure Boot certificate updates such as **KB5025885**, and require a **pre-boot PIN** to materially raise the bar for physical attackers.
Jul 24, 2026
Microsoft has published **CVE-2026-50661**, a **Windows BitLocker** security feature bypass caused by **`CWE-693: Protection Mechanism Failure`**. The flaw allows an unauthorized attacker with **physical access** to bypass BitLocker protections on affected Windows systems, including multiple supported builds of **Windows 10, Windows 11, Windows Server 2016, 2019, 2022, and 2025**, before Microsoft’s listed fixed versions. Microsoft scored the issue **CVSS 6.1 (Medium)** and released vendor advisory and patch information through MSRC. If exploited, the weakness could let an attacker recover the **Volume Master Key**, decrypt the full physical volume, and access sensitive data such as user files, system configuration, and active session tokens. The same access could enable offline tampering, including modifying binaries, changing registry hives, or planting persistent malware such as **bootkits** or malicious drivers before the device is returned to service. Reported mitigations include applying Microsoft’s updates, requiring a **pre-boot PIN** for BitLocker, and disabling the Windows Recovery Environment with: ```bash reagentc /disable ```
Jul 15, 2026
Microsoft disclosed multiple **security feature bypass** vulnerabilities affecting **Windows BitLocker** and **Windows Boot Manager**, publishing advisories for `CVE-2025-48804`, `CVE-2025-48001`, `CVE-2025-55338`, and `CVE-2022-30203`. The BitLocker issues were identified as bypass flaws rather than remote code execution bugs, indicating a risk that attackers could undermine disk encryption protections or related trust controls under certain conditions. The advisories show a recurring focus on protections tied to the Windows boot chain and full-disk encryption, with three separate BitLocker bypass CVEs and one Boot Manager bypass CVE documented by Microsoft. While Microsoft did not provide public synopses in the referenced notices, the updates signal that organizations relying on **BitLocker** and secure startup protections should prioritize review and deployment of the relevant Windows security patches to reduce the chance of pre-boot or local protection mechanisms being circumvented.
Jul 12, 2026