CWE-281 Base Draft

Improper Preservation of Permissions

This vulnerability occurs when a system fails to correctly maintain file or object permissions during operations like copying, sharing, or restoring data. As a result, these resources can end up…

Definition

What is CWE-281?

This vulnerability occurs when a system fails to correctly maintain file or object permissions during operations like copying, sharing, or restoring data. As a result, these resources can end up with weaker, more permissive security settings than the original owner intended.
This flaw typically surfaces in file management, backup systems, or data-sharing features. When an application copies a file or transfers an object between different security contexts, it must carefully replicate the original access controls. If the process simply creates a new item with default, often overly permissive, settings, it creates a security gap. Attackers can exploit this by accessing sensitive data or modifying resources they shouldn't have rights to, simply because the permissions were not preserved correctly during the operation. The core issue is a mismatch between the assumed and actual security state. Developers might trust that a restored backup or a shared file retains its original restrictions, but the underlying code failed to enforce this. To prevent this, always explicitly set and validate permissions during any data transfer or duplication, never relying on system defaults. Treat the preservation of access controls as a critical step in the data lifecycle, not an automatic side effect.
Real-world impact

Real-world CVEs caused by CWE-281

  • CVE-2002-2323

    Incorrect ACLs used when restoring backups from directories that use symbolic links.

  • CVE-2001-1515

    Automatic modification of permissions inherited from another file system.

  • CVE-2005-1920

    Permissions on backup file are created with defaults, possibly less secure than original file.

  • CVE-2001-0195

    File is made world-readable when being cloned.

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-281

  • Architecture Use safe-by-default frameworks and APIs that prevent the unsafe pattern from being expressible.
  • Implementation Validate input at trust boundaries; use allowlists, not denylists.
  • Implementation Apply the principle of least privilege to credentials, file paths, and runtime permissions.
  • Testing Cover this weakness in CI: SAST rules + targeted unit tests for the data flow.
  • Operation Monitor logs for the runtime signals listed in the next section.
Detection signals

How to detect CWE-281

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-281 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-281?

This vulnerability occurs when a system fails to correctly maintain file or object permissions during operations like copying, sharing, or restoring data. As a result, these resources can end up with weaker, more permissive security settings than the original owner intended.

How serious is CWE-281?

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-281?

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

How can I prevent CWE-281?

Use safe-by-default frameworks, validate untrusted input at trust boundaries, and apply the principle of least privilege. Cover the data-flow signature in CI with SAST.

How does Plexicus detect and fix CWE-281?

Plexicus's SAST engine matches the data-flow signature for CWE-281 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-281?

MITRE publishes the canonical definition at https://cwe.mitre.org/data/definitions/281.html. You can also reference OWASP and NIST documentation for adjacent guidance.

Related weaknesses

Weaknesses related to CWE-281

CWE-732 Parent

Incorrect Permission Assignment for Critical Resource

This vulnerability occurs when a system grants overly permissive access to a sensitive resource, allowing unauthorized users or processes…

CWE-1004 Sibling

Sensitive Cookie Without 'HttpOnly' Flag

This vulnerability occurs when an application stores sensitive data in a cookie but fails to set the 'HttpOnly' flag, leaving the cookie…

CWE-276 Sibling

Incorrect Default Permissions

This vulnerability occurs when software installation scripts set overly permissive file or directory access rights by default. Instead of…

CWE-277 Sibling

Insecure Inherited Permissions

This vulnerability occurs when an application sets default file or directory permissions that are too permissive, and these insecure…

CWE-278 Sibling

Insecure Preserved Inherited Permissions

This vulnerability occurs when a software product copies or extracts files while unintentionally preserving insecure permissions from…

CWE-279 Sibling

Incorrect Execution-Assigned Permissions

This vulnerability occurs when a running application incorrectly changes an object's access permissions, overriding the security settings…

CWE-766 Sibling

Critical Data Element Declared Public

This vulnerability occurs when a critical piece of data—like a variable, field, or class member—is mistakenly declared as public when it…

Resources

Further reading

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