EUVD-2026-56771
GHSA-3x7g-gfm7-3w86
Severity by source
AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H
Network-reachable, unauthenticated RCE with full impact; AC:H reflects the precision required to exploit integer overflow into reliable heap corruption.
Primary rating from Vendor (microsoft).
CVSS VectorVendor: microsoft
Lifecycle Timeline
3DescriptionCVE.org
Integer overflow or wraparound in Microsoft Azure Attestation service and Device Health Attestation Service allows an unauthorized attacker to execute code over a network.
AnalysisAI
Remote code execution affects Microsoft Azure Attestation service and Device Health Attestation Service via an integer overflow condition that leads to a heap-based buffer overflow (CWE-122). Unauthenticated network attackers can exploit this flaw - confirmed by PR:N in the CVSS vector - though the high attack complexity (AC:H) indicates precise exploitation conditions must be met. No public exploit code or CISA KEV listing has been identified at time of analysis, but the potential impact is critical: full compromise of confidentiality, integrity, and availability on the affected service.
Technical ContextAI
Both affected services - Microsoft Azure Attestation (a cloud service for verifying platform trustworthiness using TPM, SGX, and VBS evidence) and Device Health Attestation Service (a Windows MDM component for attesting device security posture) - process structured binary or protocol data over the network. CWE-122 (Heap-based Buffer Overflow) is the classified root-cause class, though the description specifically names an integer overflow or wraparound (more consistent with CWE-190) as the triggering condition. This is a classic two-stage exploitation pattern: an integer overflow in a size or length calculation produces an undersized heap allocation, which is then written past its bounds, resulting in a heap-based buffer overflow. The CVSS vector AV:N/AC:H reflects that exploitation is network-reachable but requires precise targeting of the overflow condition. Reported by secure@microsoft.com, indicating internal or coordinated disclosure.
RemediationAI
Apply the patch or update referenced in the Microsoft Security Response Center advisory at https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-71331. An exact fixed version number was not confirmed in the available data, so reference the advisory directly for patching guidance. For Azure Attestation (cloud-hosted), Microsoft typically deploys mitigations transparently without customer action required - verify with the MSRC advisory whether manual steps are needed. For the Device Health Attestation Service (on-premises MDM), apply the relevant Windows update via Windows Update, WSUS, or SCCM as soon as guidance is confirmed. As a compensating control while patching is validated, restrict network access to the Device Health Attestation Service endpoint to trusted MDM management networks only; note this may impact device health attestation workflows for devices not on those networks. No patch version has been independently confirmed from this data set - do not assume a specific release without verifying against the MSRC page.
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External POC / Exploit Code
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