EUVD-2026-56311
GHSA-pqxc-j7vf-j42p
Severity by source
AV:L/AC:H/PR:L/UI:N/S:C/C:H/I:N/A:N
Local low-privileged access with high complexity for timing-based exploit; scope changes as attacker reads cross-boundary memory; no integrity or availability impact applies.
Primary rating from Vendor (microsoft).
CVSS VectorVendor: microsoft
Lifecycle Timeline
3DescriptionCVE.org
No cwe for this issue in AMD Zen allows an authorized attacker to disclose information locally.
AnalysisAI
Information disclosure in AMD Zen processors on Windows allows a locally authenticated low-privileged attacker to read sensitive memory contents across security boundaries via a high-complexity microarchitectural technique. Affecting Windows versions from Windows 10 1607 to Windows 11 26H1 and Server 2012 R2 through Server 2025, this vulnerability was reported by Microsoft's security team (secure@microsoft.com) and carries a CVSS 5.6 medium score with Scope:Changed (S:C) indicating the attacker can cross a privilege boundary to reach data outside their own security context. No public exploit code exists and the vulnerability is absent from the CISA KEV catalog, though vendor-released patches are confirmed available via MSRC.
Technical ContextAI
This vulnerability is rooted in AMD Zen microprocessor hardware - a CPU-level issue rather than a software flaw, which explains why no CWE has been assigned; hardware microarchitectural vulnerabilities (speculative execution, branch predictor manipulation, shared cache state) do not map cleanly to the software-oriented CWE taxonomy. The CVSS vector's Scope:Changed (S:C) metric with High confidentiality impact (C:H) indicates the attacker can read memory or infer data outside their own privilege context, crossing a boundary such as between user-space processes or between user-space and kernel or hypervisor memory. The High attack complexity (AC:H) is characteristic of timing-sensitive microarchitectural side-channel attacks that require specific CPU state or resource contention setup to succeed. Affected CPE scope spans Windows builds from 6.3.9600 (Server 2012 R2) through 10.0.28000 (Windows 11 26H1), confirming that any Windows release running on AMD Zen hardware within those build ranges is exposed.
RemediationAI
Apply the cumulative Windows security updates corresponding to the fixed build numbers confirmed via ENISA EUVD-2026-56311: Windows Server 2025 and Server Core 10.0.26100.33296 or later, Windows Server 2022 10.0.20348.5499 or later, Windows Server 2019 and Core 10.0.17763.9115 or later, Windows Server 2016 and Core 10.0.14393.9418 or later, Windows Server 2012 R2 and Core 6.3.9600.23337 or later, Windows 11 26H1 10.0.28000.2704 or later, Windows 11 25H2 10.0.26200.9168 or later, Windows 11 24H2 10.0.26100.9168 or later, Windows 11 23H2 10.0.22631.7517 or later, Windows 10 22H2 10.0.19045.7663 or later, Windows 10 21H2 10.0.19044.7663 or later, Windows 10 1809 10.0.17763.9115 or later, and Windows 10 1607 10.0.14393.9418 or later. Consult the full MSRC advisory at https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-59130 for the authoritative update manifest. Where immediate patching is not possible on AMD Zen-based systems, restrict local interactive and remote desktop sessions to only highly trusted, privileged accounts, reducing the low-privileged local attacker access path; note this is a partial compensating control that does not eliminate the underlying hardware behavior and must not be treated as a long-term substitute for applying vendor patches.
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Same weakness CWE-200 – Information Exposure
View allSame technique Information Disclosure
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External POC / Exploit Code
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