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

Windows TCP/IP Remote Code Execution Vulnerability

IdentifiersCVE-2026-40415CWE-416· Use After Free

CVE-2026-40415 is a remote code execution vulnerability in the Windows TCP/IP component caused by a use-after-free condition. According to the provided content, an unauthorized attacker can trigger the flaw by sending specially crafted malicious network traffic to a vulnerable Windows server. Microsoft assessed the issue as affecting the Windows TCP/IP stack, with no authentication or user interaction required. The vulnerability is remotely reachable over the network and is theoretically wormable, but exploitation is considered difficult because reliable triggering requires the target system to be in sustained low-memory or memory-pressure conditions.

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 can result in remote code execution in the context of the vulnerable Windows TCP/IP component, with high impact to confidentiality, integrity, and availability. The provided content indicates Microsoft assessed all three impact dimensions as High. An attacker could potentially fully compromise the affected system, execute arbitrary code remotely, disrupt services, and use the foothold for further post-exploitation activity. Although technically wormable, exploitation is assessed as unlikely due to the requirement for rare sustained memory-pressure conditions.

Mitigation

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

No specific vendor workaround or mitigation is provided in the supplied content. The only limiting factor noted is that exploitation requires sustained low-memory or memory-pressure conditions on the target, which Microsoft states are uncommon during normal operation. As an interim risk-reduction measure, defenders should reduce exposure of vulnerable systems to untrusted network traffic and monitor for abnormal memory pressure on affected hosts, but patching is the primary remediation.

Remediation

Patch, then assume compromise.

Apply the official Microsoft security update that addresses CVE-2026-40415 in the Windows TCP/IP component. The content states that an official fix was available at publication time through Microsoft's security update process/MSRC Security Update Guide. Prioritize patching exposed or server-class Windows systems that process untrusted network traffic.
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 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 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 activity6

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