Advisory · CVE-2026-69883
Use-after-free in Windows iSCSI allows unauthenticated code execution
Windows iSCSI has a use-after-free flaw an unauthenticated attacker can trigger over the network to execute code. Microsoft rates it CVSS 3.1 9.8.
- Vendor
- Microsoft
- Product
- Windows iSCSI
- Identifier / CWE
- CVE-2026-69883
CWE-416 - Action timing
- Immediate
Explain it like I’m five
The initiator frees a structure and then keeps using it, and a remote peer can arrange what that memory means next.
- 01Reach the component
An unauthenticated attacker sends crafted network traffic to a Windows system running Windows iSCSI.
- 02Memory flaw triggers
The component mishandles the input and corrupts or reuses memory outside its intended bounds.
- 03Code runs
The attacker gains code execution in the component's context on the target system.
What happened
Microsoft disclosed CVE-2026-69883 in its October 2026 update guide: a use-after-free weakness (CWE-416) in Windows iSCSI lets an unauthorized attacker execute code over a network.
Microsoft lists the affected Windows releases in its update guide. Apply the October 2026 security updates for your release rather than relying on a version guess here.
What to do
- Inventory every Windows iSCSI deployment, including test, training, and individually managed instances.
- Apply the vendor fix or upgrade exactly as directed in the linked vendor bulletin or advisory.
- Restrict network access to Windows iSCSI while remediation is underway, especially for internet-facing instances.
- Review application and server logs for iSCSI service instability, unexpected initiators, and host crashes tied to storage traffic.
- Check for accounts, content, or configuration created outside normal change processes, and rotate exposed credentials where access cannot be ruled out.
- Verify the deployed version or patch level after remediation.
Management note
Apply the October updates to storage-connected hosts early in the cycle and review initiator lists while you are there.