CVE-2026-62813: Active Directory Use After Free Vulnerability

CVE-2026-62813 Overview

CVE-2026-62813 is a use-after-free vulnerability [CWE-416] in Microsoft Active Directory Domain Services (AD DS). An authenticated attacker can trigger the flaw over the network to execute arbitrary code within the security context of the directory service. Microsoft published the advisory through the Microsoft Security Response Center (MSRC).

The vulnerability affects the confidentiality, integrity, and availability of the domain controller. Because AD DS anchors authentication and authorization for the entire forest, successful exploitation can cascade across the enterprise identity plane.

Critical Impact
An authorized attacker with network access to a domain controller can execute code within the AD DS process, potentially leading to full domain compromise.

Affected Products

Microsoft Active Directory Domain Services (see Microsoft Security Vulnerability CVE-2026-62813 for the authoritative list of affected Windows Server builds)
Windows Server systems running the AD DS role
Domain controllers exposed to authenticated network clients

Discovery Timeline

2026-09-08 - CVE-2026-62813 published to NVD
2026-09-09 - Last updated in NVD database

Technical Details for CVE-2026-62813

Vulnerability Analysis

The vulnerability is a use-after-free condition within Active Directory Domain Services. AD DS references a memory object after it has been freed, allowing an attacker to control the contents of the reused allocation. When the stale pointer is dereferenced, the attacker-controlled data influences program flow inside the AD DS process.

Exploitation requires low privileges but high attack complexity, according to the CVSS vector published in NVD. The attacker must win a timing or state condition to place controlled data into the freed allocation before AD DS dereferences it. No user interaction is required.

Successful exploitation grants code execution in the context of the directory service, which typically runs with high privilege on the domain controller. From that foothold, an attacker can manipulate directory objects, forge credentials, or stage further intrusion across trusting systems.

Root Cause

The root cause is improper object lifetime management within AD DS request handling. A code path releases a memory object while another path retains a reference to it. Subsequent access to the dangling pointer results in memory corruption that an attacker can shape into code execution.

Attack Vector

The attack is delivered over the network to services exposed by a domain controller. The attacker must be authenticated to the directory, which any low-privileged domain account satisfies. Public technical details are limited; refer to the Microsoft Security Vulnerability CVE-2026-62813 advisory for the authoritative description of affected interfaces and preconditions.

No public proof-of-concept exploit is available at the time of publication, and the vulnerability is not listed in the CISA Known Exploited Vulnerabilities catalog.

Detection Methods for CVE-2026-62813

Indicators of Compromise

Unexpected lsass.exe or AD DS worker process crashes, dump files, or Windows Error Reporting entries on domain controllers
New or unexpected child processes spawned from AD DS-related processes on a domain controller
Anomalous LDAP, RPC, or Netlogon traffic from low-privileged domain accounts targeting domain controllers
Creation or modification of privileged directory objects, group memberships, or replication permissions without a matching change ticket

Detection Strategies

Baseline normal LDAP and RPC client behavior per account, then alert on volume spikes, malformed requests, or unusual method sequences directed at domain controllers
Monitor domain controller crash telemetry and correlate crashes with preceding authenticated network sessions
Apply behavioral endpoint detection on domain controllers to identify post-exploitation activity such as credential dumping, ticket forging, or DCSync operations

Monitoring Recommendations

Forward Windows Security, System, and Directory Service event logs to a centralized analytics platform for correlation
Enable extended AD DS auditing for directory object changes, replication requests, and account operations
Alert on service restarts of the Active Directory Domain Services role outside of maintenance windows

How to Mitigate CVE-2026-62813

Immediate Actions Required

Apply the Microsoft security update referenced in the MSRC advisory for CVE-2026-62813 to every domain controller in the forest
Prioritize patching internet-exposed and multi-tenant domain controllers first, then remaining DCs on an accelerated maintenance window
Review privileged group membership and recent directory changes for signs of unauthorized activity prior to patching
Rotate credentials for accounts that authenticated to unpatched domain controllers if exploitation is suspected

Patch Information

Microsoft has issued a security update for CVE-2026-62813. Consult the Microsoft Security Vulnerability CVE-2026-62813 page for the specific KB articles, affected Windows Server builds, and installation guidance. Domain controllers must be updated using standard Windows Server patching procedures and rebooted to apply the fix.

Workarounds

No official workaround is published; patching is the supported remediation path
Restrict network reachability of domain controllers to required subnets and administrative tiers using host-based and network firewalls
Enforce tiered administration and just-in-time access to reduce the number of accounts that can authenticate to domain controllers
Increase monitoring on domain controllers until all systems are patched and verified