The product does not release a resource after its effective lifetime has ended, i.e., after the resource is no longer needed.

Primary

Resultant

Implementation

High

Availability
DoS: Resource Consumption (Other)
DoS: Resource Consumption (Memory)
DoS: Resource Consumption (CPU)
An attacker that can influence the allocation of resources that are not properly released could deplete the available resource pool and prevent all other processes from accessing the same type of resource. Frequently-affected resources include memory, CPU, disk space, power or battery, etc.

Automated Static Analysis
Automated static analysis, commonly referred to as Static Application Security Testing (SAST), can find some instances of this weakness by analyzing source code (or binary/compiled code) without having to execute it. Typically, this is done by building a model of data flow and control flow, then searching for potentially-vulnerable patterns that connect "sources" (origins of input) with "sinks" (destinations where the data interacts with external components, a lower layer such as the OS, etc.)
High

Requirements
Language Selection

Use a language that does not allow this weakness to occur or provides constructs that make this weakness easier to avoid.
For example, languages such as Java, Ruby, and Lisp perform automatic garbage collection that releases memory for objects that have been deallocated.

Implementation
It is good practice to be responsible for freeing all resources you allocate and to be consistent with how and where you free resources in a function. If you allocate resources that you intend to free upon completion of the function, you must be sure to free the resources at all exit points for that function including error conditions.

Operation
Architecture and Design
Resource Limitation

Use resource-limiting settings provided by the operating system or environment. For example, when managing system resources in POSIX, setrlimit() can be used to set limits for certain types of resources, and getrlimit() can determine how many resources are available. However, these functions are not available on all operating systems.
When the current levels get close to the maximum that is defined for the application (see CWE-770), then limit the allocation of further resources to privileged users; alternately, begin releasing resources for less-privileged users. While this mitigation may protect the system from attack, it will not necessarily stop attackers from adversely impacting other users.
Ensure that the application performs the appropriate error checks and error handling in case resources become unavailable (CWE-703).

The following method never closes the new file handle. Given enough time, the Finalize() method for BufferReader should eventually call Close(), but there is no guarantee as to how long this action will take. In fact, there is no guarantee that Finalize() will ever be invoked. In a busy environment, the Operating System could use up all of the available file handles before the Close() function is called.

private void processFile(string fName){BufferReader fil = new BufferReader(new FileReader(fName));String line;while ((line = fil.ReadLine()) != null){processLine(line);}}

The good code example simply adds an explicit call to the Close() function when the system is done using the file. Within a simple example such as this the problem is easy to see and fix. In a real system, the problem may be considerably more obscure.

private void processFile(string fName){BufferReader fil = new BufferReader(new FileReader(fName));String line;while ((line = fil.ReadLine()) != null){processLine(line);}fil.Close();}

The following code attempts to open a new connection to a database, process the results returned by the database, and close the allocated SqlConnection object.

SqlConnection conn = new SqlConnection(connString);SqlCommand cmd = new SqlCommand(queryString);cmd.Connection = conn;conn.Open();SqlDataReader rdr = cmd.ExecuteReader();HarvestResults(rdr);conn.Connection.Close();

The problem with the above code is that if an exception occurs while executing the SQL or processing the results, the SqlConnection object is not closed. If this happens often enough, the database will run out of available cursors and not be able to execute any more SQL queries.

This code attempts to open a connection to a database and catches any exceptions that may occur.

try {Connection con = DriverManager.getConnection(some_connection_string);}catch ( Exception e ) {log( e );}

If an exception occurs after establishing the database connection and before the same connection closes, the pool of database connections may become exhausted. If the number of available connections is exceeded, other users cannot access this resource, effectively denying access to the application.

Under normal conditions the following C# code executes a database query, processes the results returned by the database, and closes the allocated SqlConnection object. But if an exception occurs while executing the SQL or processing the results, the SqlConnection object is not closed. If this happens often enough, the database will run out of available cursors and not be able to execute any more SQL queries.

...SqlConnection conn = new SqlConnection(connString);SqlCommand cmd = new SqlCommand(queryString);cmd.Connection = conn;conn.Open();SqlDataReader rdr = cmd.ExecuteReader();HarvestResults(rdr);conn.Connection.Close();...

The following C function does not close the file handle it opens if an error occurs. If the process is long-lived, the process can run out of file handles.

int decodeFile(char* fName) {
char buf[BUF_SZ];FILE* f = fopen(fName, "r");if (!f) {printf("cannot open %s\n", fName);return DECODE_FAIL;}else {
while (fgets(buf, BUF_SZ, f)) {if (!checkChecksum(buf)) {return DECODE_FAIL;}else {decodeBlock(buf);}}
}fclose(f);return DECODE_SUCCESS;
}

CVE-2007-0897
Chain: anti-virus product encounters a malformed file but returns from a function without closing a file descriptor (CWE-775) leading to file descriptor consumption (CWE-400) and failed scans.
https://www.cve.org/CVERecord?id=CVE-2007-0897

CVE-2001-0830
Sockets not properly closed when attacker repeatedly connects and disconnects from server.
https://www.cve.org/CVERecord?id=CVE-2001-0830

CVE-1999-1127
Does not shut down named pipe connections if malformed data is sent.
https://www.cve.org/CVERecord?id=CVE-1999-1127

CVE-2009-2858
Chain: memory leak (CWE-404) leads to resource exhaustion.
https://www.cve.org/CVERecord?id=CVE-2009-2858

CVE-2009-2054
Product allows exhaustion of file descriptors when processing a large number of TCP packets.
https://www.cve.org/CVERecord?id=CVE-2009-2054

CVE-2008-2122
Port scan triggers CPU consumption with processes that attempt to read data from closed sockets.
https://www.cve.org/CVERecord?id=CVE-2008-2122

CVE-2007-4103
Product allows resource exhaustion via a large number of calls that do not complete a 3-way handshake.
https://www.cve.org/CVERecord?id=CVE-2007-4103

CVE-2002-1372
Chain: Return values of file/socket operations are not checked (CWE-252), allowing resultant consumption of file descriptors (CWE-772).
https://www.cve.org/CVERecord?id=CVE-2002-1372

FIO42-C
Close files when they are no longer needed
CWE More Abstract

MEM31-C
Free dynamically allocated memory when no longer needed
CWE More Abstract

ASCSM-CWE-772

ASCRM-CWE-772

SFP14
Failure to Release Resource

Allowed
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.
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.

"Resource exhaustion" (CWE-400) is currently treated as a weakness, although it is more like a category of weaknesses that all have the same type of consequence. While this entry treats CWE-400 as a parent in view 1000, the relationship is probably more appropriately described as a chain.
Vulnerability theory is largely about how behaviors and resources interact. "Resource exhaustion" can be regarded as either a consequence or an attack, depending on the perspective. This entry is an attempt to reflect one of the underlying weaknesses that enable these attacks (or consequences) to take place.

CWE Content Team
MITRE
2009-05-13
1.4
2009-05-27

CWE Content Team
MITRE
2010-02-16
updated Demonstrative_Examples, Potential_Mitigations, Relationships

CWE Content Team
MITRE
2010-04-05
updated Potential_Mitigations

CWE Content Team
MITRE
2010-06-21
updated Potential_Mitigations

CWE Content Team
MITRE
2011-06-01
updated Common_Consequences, Relationships, Taxonomy_Mappings

CWE Content Team
MITRE
2011-06-27
updated Observed_Examples, Related_Attack_Patterns, Relationships

CWE Content Team
MITRE
2011-09-13
updated Relationships, Taxonomy_Mappings

CWE Content Team
MITRE
2012-05-11
updated Demonstrative_Examples, Relationships, Taxonomy_Mappings

CWE Content Team
MITRE
2012-10-30
updated Potential_Mitigations

CWE Content Team
MITRE
2013-02-21
updated Relationships

CWE Content Team
MITRE
2014-02-18
updated Applicable_Platforms, Demonstrative_Examples

CWE Content Team
MITRE
2014-07-30
updated Relationships, Taxonomy_Mappings

CWE Content Team
MITRE
2017-01-19
updated Relationships

CWE Content Team
MITRE
2017-11-08
updated Likelihood_of_Exploit, Taxonomy_Mappings

CWE Content Team
MITRE
2019-01-03
updated Common_Consequences, References, Relationships, Taxonomy_Mappings

CWE Content Team
MITRE
2019-06-20
updated Relationships

CWE Content Team
MITRE
2019-09-19
updated Description, Relationships

CWE Content Team
MITRE
2020-02-24
updated Applicable_Platforms, Relationships, Taxonomy_Mappings

CWE Content Team
MITRE
2020-08-20
updated Relationships

CWE Content Team
MITRE
2020-12-10
updated Relationships

CWE Content Team
MITRE
2021-03-15
updated Demonstrative_Examples

CWE Content Team
MITRE
2022-10-13
updated Relationships, Taxonomy_Mappings

CWE Content Team
MITRE
2023-01-31
updated Description

CWE Content Team
MITRE
2023-04-27
updated Relationships, Time_of_Introduction

CWE Content Team
MITRE
2023-06-29
updated Mapping_Notes

CWE Content Team
MITRE
2023-10-26
updated Observed_Examples

CWE Content Team
MITRE
2025-09-09
4.18
2025-09-09
updated Common_Consequences, Description, Diagram

CWE Content Team
MITRE
2025-12-11
4.19
2025-12-11
updated Detection_Factors, Weakness_Ordinalities