CVE-2026-62785 Overview
CVE-2026-62785 is a heap-based buffer overflow [CWE-122] in the Windows Lightweight Directory Access Protocol (LDAP) implementation. The flaw allows an unauthorized attacker to execute arbitrary code over a network. Microsoft rates the issue High with a CVSS 3.1 base score of 8.8. Exploitation requires user interaction, but no authentication or elevated privileges. The vulnerability affects a broad set of Windows client and server releases, including Windows Server 2012 through Windows Server 2025, and Windows 10 and 11 across supported feature updates. Successful exploitation results in full compromise of confidentiality, integrity, and availability on the target host.
Critical Impact
Unauthenticated attackers can achieve remote code execution against Windows systems processing attacker-controlled LDAP responses, enabling full host takeover.
Affected Products
- Microsoft Windows 10 (1607, 1809, 21H2, 22H2) across x86, x64, and ARM64
- Microsoft Windows 11 (23H2, 24H2, 25H2, 26H1) across x64 and ARM64
- Microsoft Windows Server 2012, 2012 R2, 2016, 2019, 2022, and 2025
Discovery Timeline
- 2026-08-11 - CVE-2026-62785 published to the National Vulnerability Database
- 2026-08-13 - CVE record last modified in NVD
Technical Details for CVE-2026-62785
Vulnerability Analysis
The vulnerability resides in the Windows LDAP client component, which parses directory protocol messages returned from LDAP servers. A heap-based buffer overflow occurs when the client processes a malformed response, writing attacker-controlled data beyond the bounds of a heap allocation. Because LDAP is a foundational protocol used by Active Directory clients, domain-joined workstations, and server services, the attack surface extends across the Windows ecosystem. Exploitation grants code execution in the context of the process invoking the LDAP client, which in many workflows runs with elevated system privileges.
Root Cause
The defect is classified under CWE-122, Heap-based Buffer Overflow. The LDAP parser fails to correctly validate the size of one or more length-prefixed fields inside an inbound message before copying data into a heap buffer. The mismatch between the declared and actual buffer sizes allows adjacent heap memory to be overwritten, corrupting control structures used later by the process.
Attack Vector
The CVSS vector indicates a network-reachable attack that requires user interaction. A typical exploitation path involves coercing a Windows client to connect to an attacker-controlled LDAP server, for example through a crafted URL, document, or referral response from a legitimate LDAP query. When the client parses the malicious response, the heap overflow triggers arbitrary code execution. Because privileges required are none, any user or service that initiates an LDAP connection can become the attack vehicle. The specific parsing paths and proof-of-concept details are not published; consult the Microsoft CVE-2026-62785 Advisory for technical guidance.
Detection Methods for CVE-2026-62785
Indicators of Compromise
- Outbound LDAP or LDAPS connections from workstations or servers to untrusted external IP addresses on TCP 389, 636, 3268, or 3269.
- Unexpected child processes spawned from lsass.exe, svchost.exe, or applications that embed the LDAP client library Wldap32.dll.
- Crash dumps or Windows Error Reporting events referencing Wldap32.dll with heap corruption signatures.
- Newly created services, scheduled tasks, or persistence artifacts following an LDAP session with an external host.
Detection Strategies
- Hunt for processes loading Wldap32.dll that subsequently perform code execution behaviors such as memory allocation with RWX protection, module injection, or shellcode staging.
- Correlate LDAP referral responses from external hosts with subsequent anomalous process creation on the initiating endpoint.
- Use behavioral AI identification on endpoints to flag exploitation chains that begin with a benign network protocol client and pivot into post-exploitation activity. The Singularity Platform uses behavioral models designed to identify this class of memory-corruption exploitation without prior signatures.
Monitoring Recommendations
- Enable Windows Event ID 4688 with command-line auditing and forward events to a central data lake for correlation, such as Singularity Data Lake.
- Monitor DNS and firewall logs for LDAP traffic egressing to non-corporate destinations and alert on new external LDAP referrals.
- Track patch state for Wldap32.dll and related LDAP client binaries across the fleet and alert on hosts that fall behind the Microsoft security baseline.
How to Mitigate CVE-2026-62785
Immediate Actions Required
- Apply the Microsoft security update referenced in the Microsoft CVE-2026-62785 Advisory to every affected Windows 10, Windows 11, and Windows Server build.
- Prioritize patching for domain controllers, jump hosts, and endpoints that initiate outbound LDAP queries to external destinations.
- Restrict outbound LDAP, LDAPS, and Global Catalog traffic at the perimeter so that only sanctioned directory services can be reached.
- Educate users to avoid clicking ldap:// and ldaps:// URLs delivered through email, chat, or documents, since exploitation requires user interaction.
Patch Information
Microsoft has published fixed builds through the Microsoft Security Response Center. Refer to the Microsoft CVE-2026-62785 Advisory for the KB article numbers that map to each supported Windows version and channel. Install the update through Windows Update, WSUS, or your enterprise patch management platform, then reboot to complete servicing.
Workarounds
- Block egress on TCP 389, 636, 3268, and 3269 to external networks at firewalls and web proxies where business use cases do not require it.
- Segment domain controllers and Active Directory client traffic to trusted internal ranges only, reducing exposure to hostile LDAP referrals.
- Disable LDAP referral chasing on hosts where it is not required, using Group Policy or application-level configuration.
- Use application allowlisting to prevent unexpected child processes from applications that consume LDAP responses until patches are deployed.
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
