Act nowDisclosed

Advisory · CVE-2026-70096

Heap overflow in Windows Rich Text Edit Control allows network code execution

The Windows Rich Text Edit Control has a heap-based buffer overflow an unauthenticated attacker can trigger over the network to execute code. Microsoft rates it CVSS 3.1 9.8.

Advisory published October 13, 2026Independent summary
Vendor
Microsoft
Product
Windows Rich Text Edit Control
Identifier / CWE
CVE-2026-70096
CWE-122
Action timing
Immediate
ELI5

Explain it like I’m five

The humble text box that renders formatted documents can be fed content that overflows memory and becomes code.

SIMPLIFIED_ATTACK_PATH03 STEPS
  1. 01Reach the component

    An unauthenticated attacker sends crafted network traffic to a Windows system running Windows Rich Text Edit Control.

  2. 02Memory flaw triggers

    The component mishandles the input and corrupts or reuses memory outside its intended bounds.

  3. 03Code runs

    The attacker gains code execution in the component's context on the target system.

What happened

Microsoft disclosed CVE-2026-70096 in its October 2026 update guide: a heap-based buffer overflow (CWE-122) in the Windows Rich Text Edit Control 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

  1. Inventory every Windows Rich Text Edit Control deployment, including test, training, and individually managed instances.
  2. Apply the vendor fix or upgrade exactly as directed in the linked vendor bulletin or advisory.
  3. Restrict network access to Windows Rich Text Edit Control while remediation is underway, especially for internet-facing instances.
  4. Review application and server logs for application crashes when opening rich text documents, and malformed document files in mail flow.
  5. Check for accounts, content, or configuration created outside normal change processes, and rotate exposed credentials where access cannot be ruled out.
  6. Verify the deployed version or patch level after remediation.

Management note

Rich text controls sit inside countless applications. This is a broad fleet patch, and document-handling servers deserve a look for crashes.