A heap-based buffer overflow in Windows BitLocker has been disclosed, allowing an authorized attacker or in-network attacker to execute arbitrary code locally. This flaw impacts data-at-rest protection for enterprises relying on BitLocker, necessitating prompt patching of affected systems without delay. The vulnerability, tracked as CVE-2026-69449 with a CVSS score of 6.5, has been rated 'Important' in severity and is considered to have low attack complexity and medium-level authorization requirements. Despite the code execution impact, Microsoft's Exploitability Index currently rates this vulnerability as 'Exploitation Less Likely.' However, enterprises relying on BitLocker for data-at-rest protection should not treat this classification as a reason to delay patching, given its broad client and server exposure across Windows 10, Windows 11, and Windows Server releases from 2012 to 2025. Fixes are distributed through distinct KB packages depending on platform, and IT administrators are strongly advised to prioritize deployment of the relevant September 2026 cumulative updates without delay.
We recommend you to update Windows BitLocker to given versions: KB5124012 for Windows 11 26H1 systems, KB5122871 for Windows Server 2025, KB5122882 for Windows Server 2022, KB5122876 for Windows Server 2019, and KB5123099 covering Windows Server 2016[/subscribe_to_unlock_form]
A heap-based buffer overflow in Windows BitLocker has been disclosed, allowing an authorized attacker or in-network attacker to execute arbitrary code locally. This flaw impacts data-at-rest protection for enterprises relying on BitLocker, necessitating prompt patching of affected systems without delay. The vulnerability, tracked as CVE-2026-69449 with a CVSS score of 6.5, has been rated 'Important' in severity and is considered to have low attack complexity and medium-level authorization requirements. Despite the code execution impact, Microsoft's Exploitability Index currently rates this vulnerability as 'Exploitation Less Likely.' However, enterprises relying on BitLocker for data-at-rest protection should not treat this classification as a reason to delay patching, given its broad client and server exposure across Windows 10, Windows 11, and Windows Server releases from 2012 to 2025. Fixes are distributed through distinct KB packages depending on platform, and IT administrators are strongly advised to prioritize deployment of the relevant September 2026 cumulative updates without delay.
We recommend you to update Windows BitLocker to given versions: KB5124012 for Windows 11 26H1 systems, KB5122871 for Windows Server 2025, KB5122882 for Windows Server 2022, KB5122876 for Windows Server 2019, and KB5123099 covering Windows Server 2016[emaillocker id="1283"]
The following reports contain further technical details:
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