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CVE-2025-48804 is a Windows BitLocker security feature bypass vulnerability in the Windows Recovery Environment boot chain. The flaw is rooted in Boot.sdi and ramdisk handling during Trusted WIM Boot: the boot environment validates a legitimate trusted WIM image, but does not properly bind that verification to the WIM image actually loaded from the SDI-specified offset. This acceptance of extraneous untrusted data with trusted data allows an attacker to append or reference an attacker-controlled WIM while still satisfying integrity checks on the trusted portion. In practical exploitation, a modified WinRE image can be booted while the operating system volume has already been automatically unlocked by BitLocker, enabling execution in the recovery environment with access to the decrypted volume. Public reporting also describes downgrade-based exploitation using older still-trusted boot manager binaries on systems that continue to trust legacy Secure Boot signing certificates.
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1 valid exploit after Mallory filtered fakes, detection scripts, and README-only repos.
This repository is a small, focused proof-of-concept for a BitLocker downgrade/boot-chain attack dubbed 'BitUnlocker Downgrade Attack'. It targets Windows 11 systems where BitLocker is configured in TPM-only mode and the platform still trusts Microsoft Windows PCA 2011, allowing use of an older signed bootmgfw.efi. The exploit chain described in the README uses PXE/TFTP as the practical delivery mechanism, but the author explicitly notes PXE is not fundamental to the vulnerability; the core issue is boot manager downgrade plus SDI/WIM redirection in WinRE boot flow. Repository structure is minimal: a README with operational steps and two Python utilities under scripts/. The TFTP-root directory is a staging area for PXE-served artifacts, with Boot/.gitkeep included so users can place a modified BCD there. The README provides the full operator workflow: export and modify BCD on the target from WinRE, point the recovery ramdisk SDI path to \sdi\boot_patched.sdi, stand up dnsmasq with TFTP enabled on 10.13.37.1, and let the target PXE boot to retrieve bootmgfw.efi, Boot/BCD, and the patched SDI. The main exploit capability is implemented by scripts/patch_sdi.py. That script reads a stock boot.sdi, locates the WIM and PART blob entries in the SDI blob table, appends an attacker-controlled custom WinRE.wim to the end of the SDI file with alignment padding, and patches the WIM blob entry's offset and size so the ramdisk boot loader uses the appended WIM instead of the trusted one. The script is operational rather than just demonstrative: it creates a usable boot_patched.sdi artifact intended for deployment. The README states the provided patched WIM launches cmd.exe, which gives the attacker a recovery command prompt with the BitLocker-protected OS volume already decrypted and mounted. The second script, scripts/parse_sdi.py, is a support/inspection utility rather than the exploit itself. It parses SDI headers and blob table entries, identifies blob types such as PART/WIM/BOOT, previews blob contents, detects simple file magic, and prints a layout map. Its purpose is validation and reverse-engineering of SDI structure to confirm the patched image is correctly formed. Overall, this is a real exploit repository, not merely a detector. It combines physical access, PXE/network delivery, boot configuration tampering, and crafted boot media to obtain offline access to BitLocker-protected data by coercing the system into an attacker-controlled WinRE environment.
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18 sources tracked across advisories, community write-ups, and news. New activity surfaces here as Mallory finds it.
A Windows Recovery Environment (WinRE) downgrade vulnerability involving the SDI/WIM boot mechanism that can allow an attacker with physical access to boot an attacker-modified recovery image and access a BitLocker-protected disk after it is decrypted and mounted.
One of four BitUnlocker WinRE zero-days enabling recovery-environment abuse against BitLocker-protected systems.
A physical-access BitLocker/Windows boot-chain vulnerability in Trusted WIM Boot handling that allows an attacker to supply a legitimate WIM for integrity verification while appending malicious payload data, enabling code execution and BitLocker bypass in TPM-only configurations.
A critical zero-day vulnerability in Windows Recovery Environment (WinRE) involving the SDI/WIM boot process that enables a practical BitLocker downgrade attack by booting a malicious appended WIM while integrity checks validate a legitimate one.
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