CWE-212 Base Incomplete

Improper Removal of Sensitive Information Before Storage or Transfer

This vulnerability occurs when an application stores or transmits a resource containing sensitive data without properly cleaning it first, potentially exposing that information to unauthorized…

Definition

What is CWE-212?

This vulnerability occurs when an application stores or transmits a resource containing sensitive data without properly cleaning it first, potentially exposing that information to unauthorized parties.
Many resources like documents, database entries, or network packets contain sensitive information—such as internal comments, file paths, or IP addresses—that is only relevant to a specific user or a trusted group. Before sharing that resource more broadly (e.g., exporting a document or forwarding a network request), this private data must be systematically removed, a process often called data cleansing or scrubbing. For developers, this means actively identifying and stripping sensitive metadata or embedded content. Common oversights include leaving reviewer comments in a final document draft or failing to remove internal server headers from outgoing HTTP requests. Without these checks, seemingly innocuous data sharing can inadvertently leak confidential details.
Real-world impact

Real-world CVEs caused by CWE-212

  • CVE-2019-3733

    Cryptography library does not clear heap memory before release

  • CVE-2005-0406

    Some image editors modify a JPEG image, but the original EXIF thumbnail image is left intact within the JPEG. (Also an interaction error).

  • CVE-2002-0704

    NAT feature in firewall leaks internal IP addresses in ICMP error messages.

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 PHP

This code either generates a public HTML user information page or a JSON response containing the same user information.

Vulnerable PHP 
```
// API flag, output JSON if set* 
  $json = $_GET['json']
  $username = $_GET['user']
  if(!$json)
  {
  ```
  		$record = getUserRecord($username);
  		foreach($record as $fieldName => $fieldValue)
  		{
  				if($fieldName == "email_address") {
```
// skip displaying user emails* 
  						continue;}
  				else{
  				```
  					writeToHtmlPage($fieldName,$fieldValue);
  				}
  		}
  }
  else
  {
  	$record = getUserRecord($username);
  	echo json_encode($record);
  }
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-212

  • Requirements Clearly specify which information should be regarded as private or sensitive, and require that the product offers functionality that allows the user to cleanse the sensitive information from the resource before it is published or exported to other parties.
  • Architecture and Design Compartmentalize the system to have "safe" areas where trust boundaries can be unambiguously drawn. Do not allow sensitive data to go outside of the trust boundary and always be careful when interfacing with a compartment outside of the safe area. Ensure that appropriate compartmentalization is built into the system design, and the compartmentalization allows for and reinforces privilege separation functionality. Architects and designers should rely on the principle of least privilege to decide the appropriate time to use privileges and the time to drop privileges.
  • Implementation Use naming conventions and strong types to make it easier to spot when sensitive data is being used. When creating structures, objects, or other complex entities, separate the sensitive and non-sensitive data as much as possible.
  • Implementation Avoid errors related to improper resource shutdown or release (CWE-404), which may leave the sensitive data within the resource if it is in an incomplete state.
Detection signals

How to detect CWE-212

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-212 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-212?

This vulnerability occurs when an application stores or transmits a resource containing sensitive data without properly cleaning it first, potentially exposing that information to unauthorized parties.

How serious is CWE-212?

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-212?

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

How can I prevent CWE-212?

Clearly specify which information should be regarded as private or sensitive, and require that the product offers functionality that allows the user to cleanse the sensitive information from the resource before it is published or exported to other parties. Compartmentalize the system to have "safe" areas where trust boundaries can be unambiguously drawn. Do not allow sensitive data to go outside of the trust boundary and always be careful when interfacing with a compartment outside of the safe…

How does Plexicus detect and fix CWE-212?

Plexicus's SAST engine matches the data-flow signature for CWE-212 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-212?

MITRE publishes the canonical definition at https://cwe.mitre.org/data/definitions/212.html. You can also reference OWASP and NIST documentation for adjacent guidance.

Related weaknesses

Weaknesses related to CWE-212

CWE-669 Parent

Incorrect Resource Transfer Between Spheres

This vulnerability occurs when an application incorrectly moves or shares a resource (like data, permissions, or functionality) between…

CWE-1420 Sibling

Exposure of Sensitive Information during Transient Execution

Transient execution vulnerabilities occur when a processor speculatively runs operations that don't officially commit, potentially leaking…

CWE-243 Sibling

Creation of chroot Jail Without Changing Working Directory

This vulnerability occurs when a program creates a chroot jail but fails to change its current working directory afterward. Because the…

CWE-434 Sibling

Unrestricted Upload of File with Dangerous Type

This vulnerability occurs when an application accepts file uploads without properly restricting the file types, allowing attackers to…

CWE-494 Sibling

Download of Code Without Integrity Check

This vulnerability occurs when an application fetches and runs code from an external source—like a remote server or CDN—without properly…

CWE-565 Sibling

Reliance on Cookies without Validation and Integrity Checking

This vulnerability occurs when an application uses cookies to make security decisions—like granting access or changing settings—but fails…

CWE-829 Sibling

Inclusion of Functionality from Untrusted Control Sphere

This weakness occurs when an application integrates executable code, like a library or plugin, from a source it does not fully control or…

CWE-201 Can precede

Insertion of Sensitive Information Into Sent Data

This vulnerability occurs when an application sends data to an external party, but accidentally includes sensitive information—like…

CWE-1258 Child

Exposure of Sensitive System Information Due to Uncleared Debug Information

This vulnerability occurs when hardware fails to erase sensitive data like cryptographic keys and intermediate values before entering…

Resources

Further reading

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