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CWE-307: Improper Restriction of Excessive Authentication Attempts
Weakness ID: 307Vulnerability Mapping: ALLOWED This CWE ID may be used to map to real-world vulnerabilities
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:For users who are interested in more notional aspects of a weakness. Example: educators, technical writers, and project/program managers. 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. 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. For users who wish to see all available information for the CWE/CAPEC entry. For users who want to customize what details are displayed.×
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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 Bypass Protection Mechanism
Scope: Access Control An attacker could perform an arbitrary number of authentication attempts using different passwords, and eventually gain access to the targeted account using a brute force attack.Phase(s) Mitigation Architecture and Design
Common protection mechanisms include:
- Disconnecting the user after a small number of failed attempts
- Implementing a timeout
- Locking out a targeted account
- Requiring a computational task on the user's part.
Architecture and Design
Strategy: Libraries or Frameworks
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.
799 Improper Control of Interaction Frequency 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.
1211 Authentication 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
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.
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)
Example 1
In January 2009, an attacker was able to gain administrator access to a Twitter server because the server did not restrict the number of login attempts [REF-236]. The attacker targeted a member of Twitter's support team and was able to successfully guess the member's password using a brute force attack by guessing a large number of common words. After gaining access as the member of the support staff, the attacker used the administrator panel to gain access to 33 accounts that belonged to celebrities and politicians. Ultimately, fake Twitter messages were sent that appeared to come from the compromised accounts.
Example 1 References: [REF-236] Kim Zetter. "Weak Password Brings 'Happiness' to Twitter Hacker". 2009-01-09. <https://www.wired.com/2009/01/professed-twitt/>. URL validated: 2023-04-07.
Example 2
The following code, extracted from a servlet's doPost() method, performs an authentication lookup every time the servlet is invoked.
(bad code)Example Language: JavaString username = request.getParameter("username");
String password = request.getParameter("password");
int authResult = authenticateUser(username, password);However, the software makes no attempt to restrict excessive authentication attempts.
Example 3
This code attempts to limit the number of login attempts by causing the process to sleep before completing the authentication.
(bad code)Example Language: PHP$username = $_POST['username'];
$password = $_POST['password'];
sleep(2000);
$isAuthenticated = authenticateUser($username, $password);However, there is no limit on parallel connections, so this does not increase the amount of time an attacker needs to complete an attack.
Example 4
In the following C/C++ example the validateUser method opens a socket connection, reads a username and password from the socket and attempts to authenticate the username and password.
(bad code)Example Language: Cint validateUser(char *host, int port)
{}int socket = openSocketConnection(host, port);
if (socket < 0) {printf("Unable to open socket connection");}
return(FAIL);
int isValidUser = 0;
char username[USERNAME_SIZE];
char password[PASSWORD_SIZE];
while (isValidUser == 0) {}if (getNextMessage(socket, username, USERNAME_SIZE) > 0) {if (getNextMessage(socket, password, PASSWORD_SIZE) > 0) {}isValidUser = AuthenticateUser(username, password);}
return(SUCCESS);The validateUser method will continuously check for a valid username and password without any restriction on the number of authentication attempts made. The method should limit the number of authentication attempts made to prevent brute force attacks as in the following example code.
(good code)Example Language: Cint validateUser(char *host, int port)
{}...
int count = 0;
while ((isValidUser == 0) && (count < MAX_ATTEMPTS)) {}if (getNextMessage(socket, username, USERNAME_SIZE) > 0) {if (getNextMessage(socket, password, PASSWORD_SIZE) > 0) {}isValidUser = AuthenticateUser(username, password);}
count++;
if (isValidUser) {return(SUCCESS);}
else {return(FAIL);}
Example 5
Consider this example from a real-world attack against the iPhone [REF-1218]. An attacker can use brute force methods; each time there is a failed guess, the attacker quickly cuts the power before the failed entry is recorded, effectively bypassing the intended limit on the number of failed authentication attempts. Note that this attack requires removal of the cell phone battery and connecting directly to the phone's power source, and the brute force attack is still time-consuming.
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 the REST API for a network OS has a high limit for number of connections, allowing brute force password guessingProduct does not disconnect or timeout after multiple failed logins.Product does not disconnect or timeout after multiple failed logins.Product does not disconnect or timeout after multiple failed logins.Product does not disconnect or timeout after multiple failed logins.Product does not disconnect or timeout after multiple failed logins.User accounts not disabled when they exceed a threshold; possibly a resultant problem.Ordinality Description Primary(where the weakness exists independent of other weaknesses)Method Details Dynamic Analysis with Automated Results Interpretation
According to SOAR [REF-1479], the following detection techniques may be useful:
Highly cost effective:- Web Application Scanner
- Web Services Scanner
- Database Scanners
Cost effective for partial coverage:- Host-based Vulnerability Scanners - Examine configuration for flaws, verifying that audit mechanisms work, ensure host configuration meets certain predefined criteria
Effectiveness: High
Dynamic Analysis with Manual Results Interpretation
According to SOAR [REF-1479], the following detection techniques may be useful:
Highly cost effective:- Fuzz Tester
- Framework-based Fuzzer
Cost effective for partial coverage:- Forced Path Execution
Effectiveness: High
Manual Static Analysis - Source Code
According to SOAR [REF-1479], the following detection techniques may be useful:
Highly cost effective:- Focused Manual Spotcheck - Focused manual analysis of source
- Manual Source Code Review (not inspections)
Effectiveness: High
Automated Static Analysis - Source Code
According to SOAR [REF-1479], the following detection techniques may be useful:
Cost effective for partial coverage:- Source code Weakness Analyzer
- Context-configured Source Code Weakness Analyzer
Effectiveness: SOAR Partial
Automated Static Analysis
According to SOAR [REF-1479], the following detection techniques may be useful:
Cost effective for partial coverage:- Configuration Checker
Effectiveness: SOAR Partial
Architecture or Design Review
According to SOAR [REF-1479], the following detection techniques may be useful:
Highly cost effective:- Formal Methods / Correct-By-Construction
Cost effective for partial coverage:- Inspection (IEEE 1028 standard) (can apply to requirements, design, source code, etc.)
Effectiveness: High
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.808 2010 Top 25 - Weaknesses On the Cusp MemberOf
Category - a CWE entry that contains a set of other entries that share a common characteristic.812 OWASP Top Ten 2010 Category A3 - Broken Authentication and Session Management MemberOf
Category - a CWE entry that contains a set of other entries that share a common characteristic.866 2011 Top 25 - Porous Defenses MemberOf
View - a subset of CWE entries that provides a way of examining CWE content. The two main view structures are Slices (flat lists) and Graphs (containing relationships between entries).884 CWE Cross-section MemberOf
Category - a CWE entry that contains a set of other entries that share a common characteristic.955 SFP Secondary Cluster: Unrestricted 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 Usage ALLOWED (this CWE ID may be used to map to real-world vulnerabilities)Reason Acceptable-Use Rationale
This CWE entry is at the Base level of abstraction, which is a preferred level of abstraction for mapping to the root causes of vulnerabilities. Comments
Carefully read both the name and description to ensure that this mapping is an appropriate fit. Do not try to 'force' a mapping to a lower-level Base/Variant simply to comply with this preferred level of abstraction. Mapped Taxonomy Name Node ID Fit Mapped Node Name PLOVER AUTHENT.MULTFAIL Multiple Failed Authentication Attempts not Prevented Software Fault Patterns SFP34 Unrestricted authentication [REF-45] OWASP. "OWASP Enterprise Security API (ESAPI) Project".
<https://owasp.org/www-project-enterprise-security-api/>. (URL validated: 2025-07-24)[REF-236] Kim Zetter. "Weak Password Brings 'Happiness' to Twitter Hacker". 2009-01-09.
<https://www.wired.com/2009/01/professed-twitt/>. (URL validated: 2023-04-07)[REF-1218] Graham Cluley. "This Black Box Can Brute Force Crack iPhone PIN Passcodes". The Mac Security Blog. 2015-03-16.
<https://www.intego.com/mac-security-blog/iphone-pin-pass-code/>.More information is available — Please edit the custom filter or select a different filter.Page Last Updated: January 21, 2026Use of the Common Weakness Enumeration (CWE™) and the associated references from this website are subject to the Terms of Use. CWE is sponsored by the U.S. Department of Homeland Security (DHS) Cybersecurity and Infrastructure Security Agency (CISA) and managed by the Homeland Security Systems Engineering and Development Institute (HSSEDI) which is operated by The MITRE Corporation (MITRE). Copyright © 2006–2026, The MITRE Corporation. CWE, CWSS, CWRAF, and the CWE logo are trademarks of The MITRE Corporation.



