Skip to main content
Live Webinar with SANS (June 25)— Agentic CTI Automation for Fun & ProfitRegister Free
Mallory
High

Windows Ancillary Function Driver for WinSock Elevation of Privilege Vulnerability

IdentifiersCVE-2026-35416CWE-416· Use After Free

CVE-2026-35416 is a use-after-free vulnerability in the Windows Ancillary Function Driver for WinSock (AFD.sys). According to the provided Microsoft advisory context, the flaw can be exploited by a locally authorized attacker to elevate privileges. Microsoft classifies the issue as CWE-416 and indicates exploitation requires winning a race condition, implying the vulnerable code path involves improper lifetime management of an object that can be freed and subsequently reused under specific timing conditions. The vulnerability affects the Windows Ancillary Function Driver for WinSock and can result in local privilege escalation to SYSTEM.

Share:
For your environment

Are you exposed to this one?

Mallory correlates every CVE against your assets, your vendors, and active adversary campaigns. Know which vulnerabilities matter for you, not just which ones are loud.

ANALYST BRIEF

Impact, mitigation & remediation

What it means. What to do now. Patch path, mitigations, and the assume-compromise checklist.

Impact

What an attacker gets, and what they’ve been doing with it.

Successful exploitation allows a local attacker with low privileges to elevate to SYSTEM privileges. Microsoft assessed the confidentiality, integrity, and availability impacts as High, meaning an attacker who gains SYSTEM-level execution could fully compromise the affected host, access sensitive data, modify system state, disable protections, and disrupt system availability.

Mitigation

If you can’t patch tonight, do this now.

No specific vendor mitigation beyond applying the official fix was provided in the supplied content. As interim risk reduction, limit local access for untrusted users, minimize opportunities for low-privilege code execution on affected systems, and monitor for suspicious local privilege-escalation activity involving the Windows Ancillary Function Driver for WinSock. These measures do not remove the vulnerability and should not be considered a substitute for patching.

Remediation

Patch, then assume compromise.

Apply the official Microsoft security update for CVE-2026-35416 on all affected Windows versions. Prioritize systems where local untrusted or low-privilege users can obtain code execution, as the vulnerability enables privilege escalation from a low-privilege context to SYSTEM. Standard remediation is vendor patch deployment; no alternative code-level fix information was provided in the supplied content.
PUBLIC EXPLOITS

Exploits

No public exploits tracked yet. Mallory keeps watching.

VALID 0 / 0 TOTALView more in app

No public exploit code observed for this vulnerability.

EXPOSURE SURFACE

Affected products & vendors

Products and vendors Mallory has correlated with this vulnerability. Open in Mallory to drill down to specific CPE configurations and version ranges.

VendorProductType
Microsoft CorporationWindowsoperating_system
Microsoft CorporationWindows 10 1607operating_system
Microsoft CorporationWindows 10 1809operating_system
Microsoft CorporationWindows 10 21h2operating_system
Microsoft CorporationWindows 10 22h2operating_system
Microsoft CorporationWindows 11 23h2operating_system
Microsoft CorporationWindows 11 24h2operating_system
Microsoft CorporationWindows 11 25h2operating_system
Microsoft CorporationWindows 11 26h1operating_system
Microsoft CorporationWindows Server 2012operating_system
Microsoft CorporationWindows Server 2012 R2operating_system
Microsoft CorporationWindows Server 2016operating_system
Microsoft CorporationWindows Server 2019operating_system
Microsoft CorporationWindows Server 2022operating_system
Microsoft CorporationWindows Server 2022 23h2operating_system
Microsoft CorporationWindows Server 2025operating_system
Microsoft CorporationWindows Server 23h2operating_system

Vendor-confirmed product mapping. Mallory continuously reconciles this list against your asset inventory.

What this page doesn’t show

The version that knows your environment.

This page is what’s public. Mallory adds the parts that aren’t: which of your assets are affected, which adversaries are exploiting it right now, which detections to deploy, and what to do tonight.
Exposure mapping

Query your assets running an affected version, and investigate the blast radius.

Threat actor evidence

Every observed campaign linking this CVE to a named adversary.

Associated malware

Malware families riding this exploit, with evidence and IOCs.

Detection signatures

YARA, Sigma, Snort, and vendor rules, auto-deployed to your SIEM.

Vendor-by-vendor mapping

Cross-references every affected SKU, including bundled OEM variants.

Social activity1

Community discussion across Reddit, Mastodon, and other social sources.