EUVD-2026-56381
GHSA-9758-xv2q-2mjx
Severity by source
AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
Network vector confirmed; UI:R reflects mandatory client-initiated LDAP connection; PR:N as attacker needs no target-system credentials; no scope change as impact is contained to victim process.
Primary rating from Vendor (microsoft).
CVSS VectorVendor: microsoft
Lifecycle Timeline
3DescriptionCVE.org
Heap-based buffer overflow in Windows LDAP - Lightweight Directory Access Protocol allows an unauthorized attacker to execute code over a network.
AnalysisAI
Heap-based buffer overflow in the Windows LDAP client implementation enables remote code execution against any Windows system that initiates an LDAP connection to an attacker-controlled server. The vulnerability spans an exceptionally wide set of affected Windows versions - from Windows Server 2012 through Windows 11 26H1 and Windows Server 2025 - making the potential attack surface very large. Microsoft has released patches via the standard update channel; no public exploit code or CISA KEV listing has been identified at time of analysis, though the PR:N/UI:R vector and high CIAlll impact make this a credible priority for patching.
Technical ContextAI
CWE-122 (Heap-based Buffer Overflow) identifies the root cause: the Windows LDAP client library (wldap32.dll or equivalent) fails to validate the length of data received from an LDAP server before writing it into a heap-allocated buffer. LDAP is a network protocol (typically TCP 389/636) used extensively for directory services queries - authentication, group lookups, and policy application in Active Directory environments. The overflow corrupts adjacent heap memory, providing an attacker with the primitive needed to redirect execution. Because the affected component is a client-side library, the attacker assumes the role of a malicious or compromised LDAP server rather than attacking the directory server itself. Affected CPE-derived products span the full modern Windows ecosystem from Windows 10 1607 through Windows 11 26H1 and all contemporary Windows Server releases.
RemediationAI
Apply the Microsoft-released security update via Windows Update or WSUS, targeting the specific build numbers listed per version: Windows 10 1607 and Server 2016 to 10.0.14393.9418 or later; Windows 10 1809 and Server 2019 to 10.0.17763.9115 or later; Windows 10 21H2 to 10.0.19044.7663 or later; Windows 10 22H2 to 10.0.19045.7663 or later; Windows 11 23H2 to 10.0.22631.7517 or later; Windows 11 24H2 to 10.0.26100.9168 or later; Windows Server 2025 to 10.0.26100.33296 or later; Windows 11 25H2 to 10.0.26200.9168 or later; Windows 11 26H1 to 10.0.28000.2704 or later; Windows Server 2012 to 6.2.9200.26279 or later; Windows Server 2012 R2 to 6.3.9600.23337 or later; Windows Server 2022 to 10.0.20348.5499 or later. For end-of-life systems (Server 2012/2012 R2 without ESU coverage), compensating controls include network-level filtering to restrict outbound LDAP (TCP 389, TCP 636, TCP 3268, TCP 3269) to only trusted, known-good directory servers via firewall policy - note this may impact legitimate AD authentication flows and should be validated in staging. Full advisory: https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-62785.
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Same weakness CWE-122 – Heap-based Buffer Overflow
View allSame technique Buffer Overflow
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External POC / Exploit Code
Leaving vuln.today