CWE-623 Variant Draft

Unsafe ActiveX Control Marked Safe For Scripting

This vulnerability occurs when an ActiveX control designed for limited use is incorrectly flagged as safe for scripting, allowing web pages to access its potentially dangerous functions.

Definition

What is CWE-623?

This vulnerability occurs when an ActiveX control designed for limited use is incorrectly flagged as safe for scripting, allowing web pages to access its potentially dangerous functions.
ActiveX controls are reusable software components, but some contain functionality that should only run in trusted environments. When developers or packagers mistakenly mark a restricted control as 'safe for scripting,' they remove the browser's security barrier that normally blocks untrusted web pages from interacting with it. This misconfiguration lets attackers embed malicious scripts in web pages that call the control's dangerous methods. Depending on what the control can do, this could lead to data theft, system takeover, or other exploits—effectively turning a legitimate component into an attack vector through a simple marking error.
Real-world impact

Real-world CVEs caused by CWE-623

  • CVE-2007-0617

    control allows attackers to add malicious email addresses to bypass spam limits

  • CVE-2007-0219

    web browser uses certain COM objects as ActiveX

  • CVE-2006-6510

    kiosk allows bypass to read files

How attackers exploit it

Step-by-step attacker path

  1. 1

    Identify a code path that handles untrusted input without validation.

  2. 2

    Craft a payload that exercises the unsafe behavior — injection, traversal, overflow, or logic abuse.

  3. 3

    Deliver the payload through a normal request and observe the application's reaction.

  4. 4

    Iterate until the response leaks data, executes attacker code, or escalates privileges.

Vulnerable code example

Vulnerable pseudo

MITRE has not published a code example for this CWE. The pattern below is illustrative — see Resources for canonical references.

Vulnerable pseudo 
// Example pattern — see MITRE for the canonical references.
function handleRequest(input) {
  // Untrusted input flows directly into the sensitive sink.
  return executeUnsafe(input);
}
Secure code example

Secure pseudo

Secure pseudo 
// Validate, sanitize, or use a safe API before reaching the sink.
function handleRequest(input) {
  const safe = validateAndEscape(input);
  return executeWithGuards(safe);
}
What changed: the unsafe sink is replaced (or the input is validated/escaped) so the same payload no longer triggers the weakness.
Prevention checklist

How to prevent CWE-623

  • Architecture and Design During development, do not mark it as safe for scripting.
  • System Configuration After distribution, you can set the kill bit for the control so that it is not accessible from Internet Explorer.
Detection signals

How to detect CWE-623

SAST High

Run static analysis (SAST) on the codebase looking for the unsafe pattern in the data flow.

DAST Moderate

Run dynamic application security testing against the live endpoint.

Runtime Moderate

Watch runtime logs for unusual exception traces, malformed input, or authorization bypass attempts.

Code review Moderate

Code review: flag any new code that handles input from this surface without using the validated framework helpers.

Plexicus auto-fix

Plexicus auto-detects CWE-623 and opens a fix PR in under 60 seconds.

Codex Remedium scans every commit, identifies this exact weakness, and ships a reviewer-ready pull request with the patch. No tickets. No hand-offs.

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Frequently asked questions

Frequently asked questions

What is CWE-623?

This vulnerability occurs when an ActiveX control designed for limited use is incorrectly flagged as safe for scripting, allowing web pages to access its potentially dangerous functions.

How serious is CWE-623?

MITRE has not published a likelihood-of-exploit rating for this weakness. Treat it as medium-impact until your threat model proves otherwise.

What languages or platforms are affected by CWE-623?

MITRE has not specified affected platforms for this CWE — it can apply across most application stacks.

How can I prevent CWE-623?

During development, do not mark it as safe for scripting. After distribution, you can set the kill bit for the control so that it is not accessible from Internet Explorer.

How does Plexicus detect and fix CWE-623?

Plexicus's SAST engine matches the data-flow signature for CWE-623 on every commit. When a match is found, our Codex Remedium agent opens a fix PR with the corrected code, tests, and a one-line summary for the reviewer.

Where can I learn more about CWE-623?

MITRE publishes the canonical definition at https://cwe.mitre.org/data/definitions/623.html. You can also reference OWASP and NIST documentation for adjacent guidance.

Related weaknesses

Weaknesses related to CWE-623

CWE-267 Parent

Privilege Defined With Unsafe Actions

This vulnerability occurs when a system grants a user, role, or process a specific permission that can be misused to perform dangerous,…

CWE-618 Peer

Exposed Unsafe ActiveX Method

This vulnerability occurs when an ActiveX control, designed for web browsers, exposes methods that bypass the browser's built-in security…

Resources

Further reading

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