CWE - CWE-640: Weak Password Recovery Mechanism for Forgotten Password (4.20) Common Weakness Enumeration A community-developed list of SW & HW weaknesses that can become vulnerabilities Home > CWE List > CWE-640: Weak Password Recovery Mechanism for Forgotten Password (4.20) ID Lookup: * Home * About ▼ Who We Are User Stories History Documents Videos * Learn ▼ Basics Root Cause Mapping ► Guidance Quick Tips Examples How to Contribute Weakness Content FAQs Glossary * Access Content ▼ Top-N Lists ► Top 25 Software Top Hardware Top 10 KEV Weaknesses CWE List ► Current Version Reports Visualizations Releases Archive Downloads REST API * Community ▼ News ► Current News Blog Podcast News Archive CWE Board Working Groups & Special Interest Groups Email Lists * Search ▼ Search CWE List Search Website CWE Glossary Definition CWE-640: Weak Password Recovery Mechanism for Forgotten Password Weakness ID: 640 Vulnerability Mapping : ALLOWED This CWE ID could be used to map to real-world vulnerabilities in limited situations requiring careful review (with careful review of mapping notes) Abstraction: Base Base - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource. View customized information: Conceptual For users who are interested in more notional aspects of a weakness. Example: educators, technical writers, and project/program managers. Operational For users who are concerned with the practical application and details about the nature of a weakness and how to prevent it from happening. Example: tool developers, security researchers, pen-testers, incident response analysts. Mapping Friendly For users who are mapping an issue to CWE/CAPEC IDs, i.e., finding the most appropriate CWE for a specific issue (e.g., a CVE record). Example: tool developers, security researchers. Complete For users who wish to see all available information for the CWE/CAPEC entry. Custom For users who want to customize what details are displayed. Edit Custom Filter Conceptual Operational Mapping Friendly Select All Reset Clear Submit Cancel Description The product contains a mechanism for users to recover or change their passwords without knowing the original password, but the mechanism is weak. Extended Description It is common for an application to have a mechanism that provides a means for a user to gain access to their account in the event they forget their password. Very often the password recovery mechanism is weak, which has the effect of making it more likely that it would be possible for a person other than the legitimate system user to gain access to that user's account. Weak password recovery schemes completely undermine a strong password authentication scheme. This weakness may be that the security question is too easy to guess or find an answer to (e.g. because the question is too common, or the answers can be found using social media). Or there might be an implementation weakness in the password recovery mechanism code that may for instance trick the system into e-mailing the new password to an e-mail account other than that of the user. There might be no throttling done on the rate of password resets so that a legitimate user can be denied service by an attacker if an attacker tries to recover their password in a rapid succession. The system may send the original password to the user rather than generating a new temporary password. In summary, password recovery functionality, if not carefully designed and implemented can often become the system's weakest link that can be misused in a way that would allow an attacker to gain unauthorized access to the system. Common Consequences This table specifies different individual consequences associated with the weakness. The Scope identifies the application security area that is violated, while the Impact describes the negative technical impact that arises if an adversary succeeds in exploiting this weakness. The Likelihood provides information about how likely the specific consequence is expected to be seen relative to the other consequences in the list. For example, there may be high likelihood that a weakness will be exploited to achieve a certain impact, but a low likelihood that it will be exploited to achieve a different impact. Impact Details Gain Privileges or Assume Identity Scope: Access Control An attacker could gain unauthorized access to the system by retrieving legitimate user's authentication credentials. DoS: Resource Consumption (Other) Scope: Availability An attacker could deny service to legitimate system users by launching a brute force attack on the password recovery mechanism using user ids of legitimate users. Other Scope: Integrity, Other The system's security functionality is turned against the system by the attacker. Potential Mitigations Phase(s) Mitigation Architecture and Design Make sure that all input supplied by the user to the password recovery mechanism is thoroughly filtered and validated. Architecture and Design Do not use standard weak security questions and use several security questions. Architecture and Design Make sure that there is throttling on the number of incorrect answers to a security question. Disable the password recovery functionality after a certain (small) number of incorrect guesses. Architecture and Design Require that the user properly answers the security question prior to resetting their password and sending the new password to the e-mail address of record. Architecture and Design Never allow the user to control what e-mail address the new password will be sent to in the password recovery mechanism. Architecture and Design Assign a new temporary password rather than revealing the original password. Relationships This table shows the weaknesses and high level categories that are related to this weakness. These relationships are defined as ChildOf, ParentOf, MemberOf and give insight to similar items that may exist at higher and lower levels of abstraction. In addition, relationships such as PeerOf and CanAlsoBe are defined to show similar weaknesses that the user may want to explore. Relevant to the view "Research Concepts" (View-1000) Nature Type ID Name ChildOf Class - a weakness that is described in a very abstract fashion, typically independent of any specific language or technology. More specific than a Pillar Weakness, but more general than a Base Weakness. Class level weaknesses typically describe issues in terms of 1 or 2 of the following dimensions: behavior, property, and resource. 1390 Weak Authentication Relevant to the view "Software Development" (View-699) Nature Type ID Name MemberOf Category - a CWE entry that contains a set of other entries that share a common characteristic. 255 Credentials Management Errors MemberOf Category - a CWE entry that contains a set of other entries that share a common characteristic. 840 Business Logic Errors Relevant to the view "Weaknesses for Simplified Mapping of Published Vulnerabilities" (View-1003) Nature Type ID Name ChildOf Class - a weakness that is described in a very abstract fashion, typically independent of any specific language or technology. More specific than a Pillar Weakness, but more general than a Base Weakness. Class level weaknesses typically describe issues in terms of 1 or 2 of the following dimensions: behavior, property, and resource. 287 Improper Authentication Relevant to the view "Architectural Concepts" (View-1008) Nature Type ID Name MemberOf Category - a CWE entry that contains a set of other entries that share a common characteristic. 1010 Authenticate Actors Modes Of Introduction The different Modes of Introduction provide information about how and when this weakness may be introduced. The Phase identifies a point in the life cycle at which introduction may occur, while the Note provides a typical scenario related to introduction during the given phase. Phase Note Architecture and Design COMMISSION: This weakness refers to an incorrect design related to an architectural security tactic. Implementation Applicable Platforms This listing shows possible areas for which the given weakness could appear. These may be for specific named Languages, Operating Systems, Architectures, Paradigms, Technologies, or a class of such platforms. The platform is listed along with how frequently the given weakness appears for that instance. Languages Class: Not Language-Specific (Undetermined Prevalence) Likelihood Of Exploit High Demonstrative Examples Example 1 A famous example of this type of weakness being exploited is the eBay attack. eBay always displays the user id of the highest bidder. In the final minutes of the auction, one of the bidders could try to log in as the highest bidder three times. After three incorrect log in attempts, eBay password throttling would kick in and lock out the highest bidder's account for some time. An attacker could then make their own bid and their victim would not have a chance to place the counter bid because they would be locked out. Thus an attacker could win the auction. Selected Observed Examples Note: this is a curated list of examples for users to understand the variety of ways in which this weakness can be introduced. It is not a complete list of all CVEs that are related to this CWE entry. Reference Description CVE-2025-1570 password reset functionality for a WordPress plugin allows a brute force attack of the one-time password CVE-2024-9302 password reset functionality for a WordPress plugin allows a brute force attack of the one-time password CVE-2024-5277 password recovery mechanism for AI developer toolkit does not invalidate the reset password token after it is used, allowing attackers to reuse the token to change passwords of victims CVE-2024-38287 web conference product resets passwords to random 8-digit values, allowing brute force attacks by retrieving the hash Weakness Ordinalities Ordinality Description Primary (where the weakness exists independent of other weaknesses) Memberships This MemberOf Relationships table shows additional CWE Categories and Views that reference this weakness as a member. This information is often useful in understanding where a weakness fits within the context of external information sources. Nature Type ID Name MemberOf Category - a CWE entry that contains a set of other entries that share a common characteristic. 724 OWASP Top Ten 2004 Category A3 - Broken Authentication and Session Management MemberOf Category - a CWE entry that contains a set of other entries that share a common characteristic. 930 OWASP Top Ten 2013 Category A2 - Broken Authentication and Session Management MemberOf Category - a CWE entry that contains a set of other entries that share a common characteristic. 959 SFP Secondary Cluster: Weak Cryptography MemberOf Category - a CWE entry that contains a set of other entries that share a common characteristic. 1028 OWASP Top Ten 2017 Category A2 - Broken Authentication MemberOf Category - a CWE entry that contains a set of other entries that share a common characteristic. 1353 OWASP Top Ten 2021 Category A07:2021 - Identification and Authentication Failures MemberOf Category - a CWE entry that contains a set of other entries that share a common characteristic. 1396 Comprehensive Categorization: Access Control MemberOf Category - a CWE entry that contains a set of other entries that share a common characteristic. 1442 OWASP Top Ten 2025 Category A07:2025 - Authentication Failures Vulnerability Mapping Notes Usage ALLOWED-WITH-REVIEW (this CWE ID could be used to map to real-world vulnerabilities in limited situations requiring careful review) Reason Frequent Misuse Rationale This entry appears to be frequently misused for any weakness related to password changes, even though the name focuses on "Password Recovery" for a "forgotten" password. Comments CWE-640 should only be used when there is a "password recovery" mechanism for forgotten passwords. Consider password-related entries under CWE-1390 : Weak Authentication. Notes Maintenance This entry might be reclassified as a category or "loose composite," since it lists multiple specific errors that can make the mechanism weak. However, under view 1000, it could be a weakness under protection mechanism failure, although it is different from most PMF issues since it is related to a feature that is designed to bypass a protection mechanism (specifically, the lack of knowledge of a password). Maintenance This entry probably needs to be split; see extended description. Taxonomy Mappings Mapped Taxonomy Name Node ID Fit Mapped Node Name WASC 49 Insufficient Password Recovery Related Attack Patterns CAPEC-ID Attack Pattern Name CAPEC-50 Password Recovery Exploitation References [REF-44] Michael Howard, David LeBlanc and John Viega. "24 Deadly Sins of Software Security". "Sin 19: Use of Weak Password-Based Systems." Page 279. McGraw-Hill. 2010. Content History Submissions Submission Date Submitter Organization 2008-01-30 (CWE Draft 8, 2008-01-30) Evgeny Lebanidze Cigital Modifications Modification Date Modifier Organization 2026-04-30 (CWE 4.20, 2026-04-30) CWE Content Team MITRE updated Observed_Examples 2025-12-11 (CWE 4.19, 2025-12-11) CWE Content Team MITRE updated Relationships, Weakness_Ordinalities 2023-06-29 (CWE 4.12, 2023-06-29) CWE Content Team MITRE updated Mapping_Notes 2023-04-27 (CWE 4.11, 2023-04-27) CWE Content Team MITRE updated Relationships 2023-01-31 (CWE 4.10, 2023-01-31) CWE Content Team MITRE updated Description 2022-10-13 (CWE 4.9, 2022-10-13) CWE Content Team MITRE updated Relationships 2021-10-28 (CWE 4.6, 2021-10-28) CWE Content Team MITRE updated Relationships 2019-06-20 (CWE 3.3, 2019-06-20) CWE Content Team MITRE updated Relationships 2018-03-27 (CWE 3.1, 2018-03-27) CWE Content Team MITRE updated Relationships 2017-11-08 (CWE 3.0, 2017-11-08) CWE Content Team MITRE updated Applicable_Platforms, Demonstrative_Examples, Description, Enabling_Factors_for_Exploitation, Modes_of_Introduction, Observed_Examples, Relationships 2015-12-07 (CWE 2.9, 2015-12-07) CWE Content Team MITRE updated Relationships 2014-07-30 (CWE 2.8, 2014-07-31) CWE Content Team MITRE updated Relationships 2014-06-23 (CWE 2.7, 2014-06-23) CWE Content Team MITRE updated Relationships 2012-10-30 (CWE 2.3, 2012-10-30) CWE Content Team MITRE updated Potential_Mitigations 2012-05-11 (CWE 2.2, 2012-05-15) CWE Content Team MITRE updated References, Relationships 2011-06-01 (CWE 1.13, 2011-06-01) CWE Content Team MITRE updated Common_Consequences 2011-03-29 (CWE 1.12, 2011-03-30) CWE Content Team MITRE updated Relationships 2010-12-13 (CWE 1.11, 2010-12-13) CWE Content Team MITRE updated Common_Consequences 2010-02-16 (CWE 1.8, 2010-02-16) CWE Content Team MITRE updated Taxonomy_Mappings 2009-05-27 (CWE 1.4, 2009-05-27) CWE Content Team MITRE updated Related_Attack_Patterns 2009-03-10 (CWE 1.3, 2009-03-10) CWE Content Team MITRE updated Relationships 2008-09-08 (CWE 1.0, 2008-09-09) CWE Content Team MITRE updated Common_Consequences, Description, Maintenance_Notes, Name, Relationships Previous Entry Names Change Date Previous Entry Name 2008-09-09 Weak Password Recovery Mechanism More information is available -- Please edit the custom filter or select a different filter. 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