CWE-529 Variant Incomplete

Exposure of Access Control List Files to an Unauthorized Control Sphere

This vulnerability occurs when an application stores sensitive access control list (ACL) files in a location that is accessible to unauthorized users or systems.

Definition

What is CWE-529?

This vulnerability occurs when an application stores sensitive access control list (ACL) files in a location that is accessible to unauthorized users or systems.
When ACL files—which define permissions and user roles—are placed in publicly accessible directories, attackers can easily retrieve them. This exposure often happens due to misconfigured web server permissions, insecure default settings, or deployment errors that leave configuration files in web-accessible folders. Access to these files provides attackers with a blueprint of your security model. They can analyze user privileges, identify administrative accounts, and discover trusted systems to target. This intelligence allows attackers to craft precise attacks that bypass your intended security controls, potentially leading to unauthorized data access or system takeover.
Real-world impact

Real-world CVEs caused by CWE-529

No public CVE references are linked to this CWE in MITRE's catalog yet.

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-529

  • System Configuration Protect access control list files.
Detection signals

How to detect CWE-529

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-529 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-529?

This vulnerability occurs when an application stores sensitive access control list (ACL) files in a location that is accessible to unauthorized users or systems.

How serious is CWE-529?

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-529?

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

How can I prevent CWE-529?

Protect access control list files.

How does Plexicus detect and fix CWE-529?

Plexicus's SAST engine matches the data-flow signature for CWE-529 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-529?

MITRE publishes the canonical definition at https://cwe.mitre.org/data/definitions/529.html. You can also reference OWASP and NIST documentation for adjacent guidance.

Related weaknesses

Weaknesses related to CWE-529

CWE-552 Parent

Files or Directories Accessible to External Parties

This vulnerability occurs when an application exposes files or directories to users who shouldn't have access to them.

CWE-219 Sibling

Storage of File with Sensitive Data Under Web Root

This vulnerability occurs when an application saves sensitive files, such as configuration data or private keys, inside the web server's…

CWE-220 Sibling

Storage of File With Sensitive Data Under FTP Root

This vulnerability occurs when an application saves sensitive files, such as configuration or user data, within the directory served by an…

CWE-527 Sibling

Exposure of Version-Control Repository to an Unauthorized Control Sphere

This vulnerability occurs when a version control repository, like Git or SVN, is accidentally placed in a location accessible to…

CWE-528 Sibling

Exposure of Core Dump File to an Unauthorized Control Sphere

This vulnerability occurs when an application creates a core dump file (a snapshot of memory at the time of a crash) and places it in a…

CWE-530 Sibling

Exposure of Backup File to an Unauthorized Control Sphere

This vulnerability occurs when backup or temporary files are stored in locations that unauthorized users can access, such as web…

CWE-539 Sibling

Use of Persistent Cookies Containing Sensitive Information

This vulnerability occurs when a web application stores sensitive data, like authentication details or personal information, within…

CWE-553 Sibling

Command Shell in Externally Accessible Directory

This vulnerability occurs when a command shell script is placed in a web-accessible directory, such as /cgi-bin/. Attackers can directly…

Resources

Further reading

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