The product does not properly control situations in which an adversary can cause the product to consume or produce excessive resources without requiring the adversary to invest equivalent work or otherwise prove authorization, i.e., the adversary's influence is "asymmetric."
This can lead to poor performance due to "amplification" of resource consumption, typically in a non-linear fashion. This situation is worsened if the product allows malicious users or attackers to consume more resources than their access level permits.

Resultant

Architecture and Design

Implementation

Operation

Availability
DoS: Amplification
DoS: Resource Consumption (CPU)
DoS: Resource Consumption (Memory)
DoS: Resource Consumption (Other)
High
Sometimes this is a factor in "flood" attacks, but other types of amplification exist.

Architecture and Design
An application must make resources available to a client commensurate with the client's access level.

Architecture and Design
An application must, at all times, keep track of allocated resources and meter their usage appropriately.

System Configuration
Consider disabling resource-intensive algorithms on the server side, such as Diffie-Hellman key exchange.
High
Business requirements may prevent disabling resource-intensive algorithms.

This code listens on a port for DNS requests and sends the result to the requesting address.

sock = socket.socket(socket.AF_INET, socket.SOCK_DGRAM)sock.bind( (UDP_IP,UDP_PORT) )while true:
data = sock.recvfrom(1024)if not data:break
(requestIP, nameToResolve) = parseUDPpacket(data)record = resolveName(nameToResolve)sendResponse(requestIP,record)

This code sends a DNS record to a requesting IP address. UDP allows the source IP address to be easily changed ('spoofed'), thus allowing an attacker to redirect responses to a target, which may be then be overwhelmed by the network traffic.

This function prints the contents of a specified file requested by a user.

function printFile($username,$filename){

//read file into string
$file = file_get_contents($filename);if ($file && isOwnerOf($username,$filename)){echo $file;return true;}else{echo 'You are not authorized to view this file';}return false;
}

This code first reads a specified file into memory, then prints the file if the user is authorized to see its contents. The read of the file into memory may be resource intensive and is unnecessary if the user is not allowed to see the file anyway.

The DTD and the very brief XML below illustrate what is meant by an XML bomb. The ZERO entity contains one character, the letter A. The choice of entity name ZERO is being used to indicate length equivalent to that exponent on two, that is, the length of ZERO is 2^0. Similarly, ONE refers to ZERO twice, therefore the XML parser will expand ONE to a length of 2, or 2^1. Ultimately, we reach entity THIRTYTWO, which will expand to 2^32 characters in length, or 4 GB, probably consuming far more data than expected.

<?xml version="1.0"?><!DOCTYPE MaliciousDTD [<!ENTITY ZERO "A"><!ENTITY ONE "&ZERO;&ZERO;"><!ENTITY TWO "&ONE;&ONE;">...<!ENTITY THIRTYTWO "&THIRTYONE;&THIRTYONE;">]><data>&THIRTYTWO;</data>

This example attempts to check if an input string is a "sentence" [REF-1164].

var test_string = "Bad characters: $@#";
var bad_pattern = /^(\w+\s?)*$/i;
var result = test_string.search(bad_pattern);

The regular expression has a vulnerable backtracking clause inside (\w+\s?)*$ which can be triggered to cause a Denial of Service by processing particular phrases.
To fix the backtracking problem, backtracking is removed with the ?= portion of the expression which changes it to a lookahead and the \2 which prevents the backtracking. The modified example is:

var test_string = "Bad characters: $@#";
var good_pattern = /^((?=(\w+))\2\s?)*$/i;
var result = test_string.search(good_pattern);

Note that [REF-1164] has a more thorough (and lengthy) explanation of everything going on within the RegEx.

An adversary can cause significant resource
consumption on a server by filtering the cryptographic
algorithms offered by the client to the ones that are the
most resource-intensive on the server side. After
discovering which cryptographic algorithms are supported
by the server, a malicious client can send the initial
cryptographic handshake messages that contains only the
resource-intensive algorithms. For some cryptographic
protocols, these messages can be completely
prefabricated, as the resource-intensive part of the
handshake happens on the server-side first (such as TLS),
rather than on the client side. In the case of
cryptographic protocols where the resource-intensive part
should happen on the client-side first (such as SSH), a
malicious client can send a forged/precalculated
computation result, which seems correct to the server, so
the resource-intensive part of the handshake is going to
happen on the server side. A malicious client is required
to send only the initial messages of a cryptographic
handshake to initiate the resource-consuming part of the
cryptographic handshake. These messages are usually
small, and generating them requires minimal computational
effort, enabling a denial-of-service attack. An
additional risk is the fact that higher key size
increases the effectiveness of the attack. Cryptographic
protocols where the clients have influence over the size
of the used key (such as TLS 1.3 or SSH) are most at
risk, as the client can enforce the highest key size
supported by the server.

CVE-1999-0513
Classic "Smurf" attack, using spoofed ICMP packets to broadcast addresses.
https://www.cve.org/CVERecord?id=CVE-1999-0513

CVE-2003-1564
Parsing library allows XML bomb
https://www.cve.org/CVERecord?id=CVE-2003-1564

CVE-2004-2458
Tool creates directories before authenticating user.
https://www.cve.org/CVERecord?id=CVE-2004-2458

CVE-2020-10735
Python has "quadratic complexity" issue when converting string to int with many digits in unexpected bases
https://www.cve.org/CVERecord?id=CVE-2020-10735

CVE-2020-5243
server allows ReDOS with crafted User-Agent strings, due to overlapping capture groups that cause excessive backtracking.
https://www.cve.org/CVERecord?id=CVE-2020-5243

CVE-2013-5211
composite: NTP feature generates large responses (high amplification factor) with spoofed UDP source addresses.
https://www.cve.org/CVERecord?id=CVE-2013-5211

CVE-2002-20001
Diffie-Hellman (DHE) Key Agreement Protocol allows attackers to send arbitrary numbers that are not public keys, which causes the server to perform expensive, unnecessary computation of modular exponentiation.
https://www.cve.org/CVERecord?id=CVE-2002-20001

CVE-2022-40735
The Diffie-Hellman Key Agreement Protocol allows use of long exponents, which are more computationally expensive than using certain "short exponents" with particular properties.
https://www.cve.org/CVERecord?id=CVE-2022-40735

Asymmetric resource consumption (amplification)

A9
Denial of Service
CWE More Specific

41
XML Attribute Blowup

TPS00-J
Use thread pools to enable graceful degradation of service during traffic bursts

FIO04-J
Release resources when they are no longer needed

Allowed-with-Review
This CWE entry is a Class and might have Base-level children that would be more appropriate
Examine children of this entry to see if there is a better fit

PLOVER
2006-07-19
Draft 3
2006-07-19

Eric Dalci
Cigital
2008-07-01
updated Time_of_Introduction

CWE Content Team
MITRE
2008-09-08
updated Relationships, Other_Notes, Taxonomy_Mappings

CWE Content Team
MITRE
2008-10-14
updated Description

CWE Content Team
MITRE
2009-07-27
updated Common_Consequences, Other_Notes

CWE Content Team
MITRE
2010-02-16
updated Taxonomy_Mappings

CWE Content Team
MITRE
2010-12-13
updated Description

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

CWE Content Team
MITRE
2011-06-27
updated Common_Consequences

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

CWE Content Team
MITRE
2012-10-30
updated Potential_Mitigations

CWE Content Team
MITRE
2014-07-30
updated Relationships

CWE Content Team
MITRE
2015-12-07
updated Relationships

CWE Content Team
MITRE
2017-11-08
updated Applicable_Platforms, Functional_Areas

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

CWE Content Team
MITRE
2019-06-20
updated Relationships

CWE Content Team
MITRE
2020-02-24
updated Relationships

CWE Content Team
MITRE
2023-01-31
updated Applicable_Platforms, Common_Consequences, Demonstrative_Examples, Description, Observed_Examples, Potential_Mitigations, References, Time_of_Introduction

CWE Content Team
MITRE
2023-04-27
updated Relationships

CWE Content Team
MITRE
2023-06-29
updated Mapping_Notes, Relationships

CWE Content Team
MITRE
2024-02-29
4.14
2024-02-29
updated Demonstrative_Examples

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

Szilárd Pfeiffer
Balasys IT Security
2021-11-11
Submitted content that led to modifications in applicable platforms, common consequences, potential mitigations, demonstrative examples, observed examples.