CWE-620 Base Draft

Unverified Password Change

This vulnerability occurs when an application allows a user to set a new password without first verifying their identity through the old password or a secure secondary authentication method.

Definition

What is CWE-620?

This vulnerability occurs when an application allows a user to set a new password without first verifying their identity through the old password or a secure secondary authentication method.
This flaw creates a major security gap, as an attacker who can access the password change function (for example, through a predictable user ID or a cross-site request forgery attack) can reset another user's credentials. Without proper verification, the system implicitly trusts that the person requesting the change is the legitimate account holder, leading to a complete account takeover. To prevent this, developers must always require proof of identity before processing a password reset. The standard practice is to require the user's current password for a voluntary change, or to use a time-limited, single-use token sent to a pre-verified email or phone for a recovery scenario. This ensures that control of the account is never relinquished based on a simple request alone.
Real-world impact

Real-world CVEs caused by CWE-620

  • CVE-2007-0681

    Web app allows remote attackers to change the passwords of arbitrary users without providing the original password, and possibly perform other unauthorized actions.

  • CVE-2000-0944

    Web application password change utility doesn't check the original password.

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 changes a user's password.

Vulnerable PHP 
$user = $_GET['user'];
  $pass = $_GET['pass'];
  $checkpass = $_GET['checkpass'];
  if ($pass == $checkpass) {
  	SetUserPassword($user, $pass);
  }
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-620

  • Architecture and Design When prompting for a password change, force the user to provide the original password in addition to the new password.
  • Architecture and Design Do not use "forgotten password" functionality. But if you must, ensure that you are only providing information to the actual user, e.g. by using an email address or challenge question that the legitimate user already provided in the past; do not allow the current user to change this identity information until the correct password has been provided.
Detection signals

How to detect CWE-620

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-620 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-620?

This vulnerability occurs when an application allows a user to set a new password without first verifying their identity through the old password or a secure secondary authentication method.

How serious is CWE-620?

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-620?

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

How can I prevent CWE-620?

When prompting for a password change, force the user to provide the original password in addition to the new password. Do not use "forgotten password" functionality. But if you must, ensure that you are only providing information to the actual user, e.g. by using an email address or challenge question that the legitimate user already provided in the past; do not allow the current user to change this identity information until the correct password has been provided.

How does Plexicus detect and fix CWE-620?

Plexicus's SAST engine matches the data-flow signature for CWE-620 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-620?

MITRE publishes the canonical definition at https://cwe.mitre.org/data/definitions/620.html. You can also reference OWASP and NIST documentation for adjacent guidance.

Related weaknesses

Weaknesses related to CWE-620

CWE-1390 Parent

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This vulnerability occurs when a system's login or identity verification process is too easy to bypass or fool. While it attempts to check…

CWE-1391 Sibling

Use of Weak Credentials

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CWE-262 Sibling

Not Using Password Aging

This vulnerability occurs when a system lacks password expiration policies, allowing users to keep the same password indefinitely.

CWE-263 Sibling

Password Aging with Long Expiration

The system enforces password changes, but the time allowed between changes is excessively long, weakening security.

CWE-289 Sibling

Authentication Bypass by Alternate Name

This vulnerability occurs when a system checks access based on a resource or user name, but fails to account for all the different names…

CWE-290 Sibling

Authentication Bypass by Spoofing

This weakness occurs when an application's authentication system can be tricked into accepting forged or manipulated credentials, allowing…

CWE-294 Sibling

Authentication Bypass by Capture-replay

This vulnerability occurs when an attacker can intercept and record legitimate authentication traffic, then replay it later to gain…

CWE-301 Sibling

Reflection Attack in an Authentication Protocol

A reflection attack is a flaw in mutual authentication protocols that allows an attacker to impersonate a legitimate user without knowing…

CWE-302 Sibling

Authentication Bypass by Assumed-Immutable Data

This vulnerability occurs when an authentication system incorrectly treats certain data as unchangeable, when in fact an attacker can…

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