CWE-1321
AllowedImproperly Controlled Modification of Object Prototype Attributes ('Prototype Pollution')
Abstraction: Variant · Status: Incomplete
The product receives input from an upstream component that specifies attributes that are to be initialized or updated in an object, but it does not properly control modifications of attributes of the object prototype.
866 vulnerabilities reference this CWE, most recent first.
GHSA-84P7-FH9C-6G8H
Vulnerability from github – Published: 2021-09-20 19:52 – Updated: 2021-09-16 21:30Impact
When copying properties from a source object to a target object, the target object can gain access to certain properties of the source object and modify their content.
Patches
The problem was patch with a more agressive discovery of secured properties to filter out.
{
"affected": [
{
"package": {
"ecosystem": "npm",
"name": "mixme"
},
"ranges": [
{
"events": [
{
"introduced": "0"
},
{
"fixed": "0.5.2"
}
],
"type": "ECOSYSTEM"
}
]
}
],
"aliases": [],
"database_specific": {
"cwe_ids": [
"CWE-1321"
],
"github_reviewed": true,
"github_reviewed_at": "2021-09-16T21:30:18Z",
"nvd_published_at": null,
"severity": "HIGH"
},
"details": "### Impact\nWhen copying properties from a source object to a target object, the target object can gain access to certain properties of the source object and modify their content.\n\n### Patches\nThe problem was patch with a more agressive discovery of secured properties to filter out.\n",
"id": "GHSA-84p7-fh9c-6g8h",
"modified": "2021-09-16T21:30:18Z",
"published": "2021-09-20T19:52:24Z",
"references": [
{
"type": "WEB",
"url": "https://github.com/adaltas/node-mixme/security/advisories/GHSA-84p7-fh9c-6g8h"
},
{
"type": "WEB",
"url": "https://github.com/adaltas/node-mixme/issues/1"
},
{
"type": "WEB",
"url": "https://github.com/adaltas/node-mixme/issues/2"
},
{
"type": "WEB",
"url": "https://github.com/adaltas/node-mixme/commit/db70fe9bcbba451e9f8bd794a9fa7cdfa00125ad"
},
{
"type": "PACKAGE",
"url": "https://github.com/adaltas/node-mixme"
},
{
"type": "ADVISORY",
"url": "https://github.com/advisories/GHSA-79jw-6wg7-r9g4"
}
],
"schema_version": "1.4.0",
"severity": [],
"summary": "Prototype Pollution in mixme"
}
GHSA-85CP-P426-42F5
Vulnerability from github – Published: 2021-05-06 18:12 – Updated: 2021-05-05 18:16All versions of package deep-get-set prior to version 1.1.1 are vulnerable to Prototype Pollution via the main function.
{
"affected": [
{
"package": {
"ecosystem": "npm",
"name": "deep-get-set"
},
"ranges": [
{
"events": [
{
"introduced": "0"
},
{
"fixed": "1.1.1"
}
],
"type": "ECOSYSTEM"
}
]
}
],
"aliases": [
"CVE-2020-7715"
],
"database_specific": {
"cwe_ids": [
"CWE-1321"
],
"github_reviewed": true,
"github_reviewed_at": "2021-05-05T18:16:57Z",
"nvd_published_at": "2020-09-01T10:15:00Z",
"severity": "HIGH"
},
"details": "All versions of package deep-get-set prior to version 1.1.1 are vulnerable to Prototype Pollution via the main function.",
"id": "GHSA-85cp-p426-42f5",
"modified": "2021-05-05T18:16:57Z",
"published": "2021-05-06T18:12:59Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2020-7715"
},
{
"type": "WEB",
"url": "https://github.com/acstll/deep-get-set/commit/a127e65bc77ff5707a6a103819e140d11475c5f4"
},
{
"type": "WEB",
"url": "https://snyk.io/vuln/SNYK-JS-DEEPGETSET-598666"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H",
"type": "CVSS_V3"
}
],
"summary": "Prototype Pollution in deep-get-set"
}
GHSA-85G2-29M8-QF2P
Vulnerability from github – Published: 2021-03-19 21:18 – Updated: 2021-03-16 22:49Prototype pollution vulnerability in 'object-collider' versions 1.0.0 through 1.0.3 allows attacker to cause a denial of service and may lead to remote code execution.
{
"affected": [
{
"package": {
"ecosystem": "npm",
"name": "object-collider"
},
"ranges": [
{
"events": [
{
"introduced": "1.0.0"
},
{
"fixed": "1.0.4"
}
],
"type": "ECOSYSTEM"
}
]
}
],
"aliases": [
"CVE-2021-25914"
],
"database_specific": {
"cwe_ids": [
"CWE-1321"
],
"github_reviewed": true,
"github_reviewed_at": "2021-03-16T22:49:14Z",
"nvd_published_at": "2021-03-01T18:15:00Z",
"severity": "CRITICAL"
},
"details": "Prototype pollution vulnerability in \u0027object-collider\u0027 versions 1.0.0 through 1.0.3 allows attacker to cause a denial of service and may lead to remote code execution.",
"id": "GHSA-85g2-29m8-qf2p",
"modified": "2021-03-16T22:49:14Z",
"published": "2021-03-19T21:18:33Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2021-25914"
},
{
"type": "WEB",
"url": "https://github.com/FireBlinkLTD/object-collider/commit/321f75a7f8e7b3393e5b7dd6dd9ab26ede5906e5"
},
{
"type": "WEB",
"url": "https://www.whitesourcesoftware.com/vulnerability-database/CVE-2021-25914"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H",
"type": "CVSS_V3"
}
],
"summary": "Prototype Pollution Vulnerability in object-collider"
}
GHSA-866W-WM4H-95C6
Vulnerability from github – Published: 2022-10-12 12:00 – Updated: 2024-04-22 23:20Prototype pollution vulnerability in function resolveShims in resolve-shims.js in thlorenz browserify-shim 3.8.15 via the k variable in resolve-shims.js.
{
"affected": [
{
"database_specific": {
"last_known_affected_version_range": "\u003c= 3.8.15"
},
"package": {
"ecosystem": "npm",
"name": "browserify-shim"
},
"ranges": [
{
"events": [
{
"introduced": "0"
},
{
"fixed": "3.8.16"
}
],
"type": "ECOSYSTEM"
}
]
}
],
"aliases": [
"CVE-2022-37617"
],
"database_specific": {
"cwe_ids": [
"CWE-1321"
],
"github_reviewed": true,
"github_reviewed_at": "2024-04-22T23:20:58Z",
"nvd_published_at": "2022-10-11T23:15:00Z",
"severity": "CRITICAL"
},
"details": "Prototype pollution vulnerability in function `resolveShims` in resolve-shims.js in thlorenz browserify-shim 3.8.15 via the `k` variable in resolve-shims.js.",
"id": "GHSA-866w-wm4h-95c6",
"modified": "2024-04-22T23:20:58Z",
"published": "2022-10-12T12:00:18Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2022-37617"
},
{
"type": "WEB",
"url": "https://github.com/thlorenz/browserify-shim/issues/245"
},
{
"type": "WEB",
"url": "https://github.com/thlorenz/browserify-shim/pull/246"
},
{
"type": "WEB",
"url": "https://github.com/thlorenz/browserify-shim/commit/97855e622b6dcd117c77e6583701962ff45e7338"
},
{
"type": "PACKAGE",
"url": "https://github.com/thlorenz/browserify-shim"
},
{
"type": "WEB",
"url": "https://github.com/thlorenz/browserify-shim/blob/464b32bbe142664cd9796059798f6c738ea3de8f/lib/resolve-shims.js#L130"
},
{
"type": "WEB",
"url": "https://github.com/thlorenz/browserify-shim/blob/464b32bbe142664cd9796059798f6c738ea3de8f/lib/resolve-shims.js#L158"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H",
"type": "CVSS_V3"
}
],
"summary": "thlorenz browserify-shim vulnerable to prototype pollution"
}
GHSA-866W-XMHQ-WJ7X
Vulnerability from github – Published: 2026-07-24 15:58 – Updated: 2026-07-24 15:58If you use remote form functions, have an input field of type file, and accept arbitrary user-controlled path names for the field, then you are vulnerable to a prototype pollution attack where the attacker can remove e.g. methods on the prototype.
{
"affected": [
{
"database_specific": {
"last_known_affected_version_range": "\u003c= 2.69.0"
},
"package": {
"ecosystem": "npm",
"name": "@sveltejs/kit"
},
"ranges": [
{
"events": [
{
"introduced": "0"
},
{
"fixed": "2.69.1"
}
],
"type": "ECOSYSTEM"
}
]
}
],
"aliases": [],
"database_specific": {
"cwe_ids": [
"CWE-1321"
],
"github_reviewed": true,
"github_reviewed_at": "2026-07-24T15:58:05Z",
"nvd_published_at": null,
"severity": "MODERATE"
},
"details": "If you use remote form functions, have an input field of type `file`, and accept arbitrary user-controlled path names for the field, then you are vulnerable to a prototype pollution attack where the attacker can remove e.g. methods on the prototype.",
"id": "GHSA-866w-xmhq-wj7x",
"modified": "2026-07-24T15:58:05Z",
"published": "2026-07-24T15:58:05Z",
"references": [
{
"type": "WEB",
"url": "https://github.com/sveltejs/kit/security/advisories/GHSA-866w-xmhq-wj7x"
},
{
"type": "WEB",
"url": "https://github.com/sveltejs/kit/pull/16218"
},
{
"type": "WEB",
"url": "https://github.com/sveltejs/kit/commit/df32f6fe86cdd0b68b650e3e4631e5896453dcd3"
},
{
"type": "PACKAGE",
"url": "https://github.com/sveltejs/kit"
},
{
"type": "WEB",
"url": "https://github.com/sveltejs/kit/releases/tag/@sveltejs/kit@2.69.1"
},
{
"type": "WEB",
"url": "https://github.com/sveltejs/kit/releases/tag/@sveltejs/kit@3.0.0-next.7"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:L",
"type": "CVSS_V3"
}
],
"summary": "SvelteKit: Prototype pollution in file input deletion path in remote-function forms"
}
GHSA-876P-C77M-X2HC
Vulnerability from github – Published: 2024-07-01 15:32 – Updated: 2024-09-04 16:39ag-grid-community v31.3.2 and ag-grid-enterprise v31.3.2 were discovered to contain a prototype pollution via the _.mergeDeep function. This vulnerability allows attackers to execute arbitrary code or cause a Denial of Service (DoS) via injecting arbitrary properties. Prior versions were also found to be affected.
{
"affected": [
{
"package": {
"ecosystem": "npm",
"name": "ag-grid-enterprise"
},
"ranges": [
{
"events": [
{
"introduced": "0"
},
{
"fixed": "31.3.4"
}
],
"type": "ECOSYSTEM"
}
]
},
{
"package": {
"ecosystem": "npm",
"name": "ag-grid-community"
},
"ranges": [
{
"events": [
{
"introduced": "0"
},
{
"fixed": "31.3.4"
}
],
"type": "ECOSYSTEM"
}
]
}
],
"aliases": [
"CVE-2024-38996"
],
"database_specific": {
"cwe_ids": [
"CWE-1321"
],
"github_reviewed": true,
"github_reviewed_at": "2024-07-01T22:34:03Z",
"nvd_published_at": "2024-07-01T13:15:05Z",
"severity": "HIGH"
},
"details": "ag-grid-community v31.3.2 and ag-grid-enterprise v31.3.2 were discovered to contain a prototype pollution via the _.mergeDeep function. This vulnerability allows attackers to execute arbitrary code or cause a Denial of Service (DoS) via injecting arbitrary properties. Prior versions were also found to be affected.",
"id": "GHSA-876p-c77m-x2hc",
"modified": "2024-09-04T16:39:10Z",
"published": "2024-07-01T15:32:17Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2024-38996"
},
{
"type": "WEB",
"url": "https://github.com/ag-grid/ag-grid/pull/8290"
},
{
"type": "WEB",
"url": "https://gist.github.com/mestrtee/18e8c27f3a6376e7cf082cfe1ca766fa"
},
{
"type": "WEB",
"url": "https://gist.github.com/mestrtee/c1590660750744f25e86ba1bf240844b"
},
{
"type": "WEB",
"url": "https://gist.github.com/mestrtee/f8037d492dab0d77bca719e05d31c08b"
},
{
"type": "PACKAGE",
"url": "https://github.com/ag-grid/ag-grid"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H",
"type": "CVSS_V3"
},
{
"score": "CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N/E:P",
"type": "CVSS_V4"
}
],
"summary": "Prototype pollution in ag-grid-community via the _.mergeDeep function"
}
GHSA-87QP-7CW8-8Q9C
Vulnerability from github – Published: 2024-03-25 06:30 – Updated: 2024-03-27 21:57Duplicate Advisory
This advisory has been withdrawn because it is a duplicate of GHSA-2g4c-8fpm-c46v. This link is maintained to preserve external references.
Original Description
Versions of the package web3-utils before 4.2.1 are vulnerable to Prototype Pollution via the utility functions format and mergeDeep, due to insecure recursive merge. An attacker can manipulate an object's prototype, potentially leading to the alteration of the behavior of all objects inheriting from the affected prototype by passing specially crafted input to these functions.
{
"affected": [
{
"package": {
"ecosystem": "npm",
"name": "web3-utils"
},
"ranges": [
{
"events": [
{
"introduced": "0"
},
{
"fixed": "4.2.1"
}
],
"type": "ECOSYSTEM"
}
]
}
],
"aliases": [],
"database_specific": {
"cwe_ids": [
"CWE-1321"
],
"github_reviewed": true,
"github_reviewed_at": "2024-03-25T19:36:43Z",
"nvd_published_at": "2024-03-25T05:15:50Z",
"severity": "HIGH"
},
"details": "## Duplicate Advisory\nThis advisory has been withdrawn because it is a duplicate of GHSA-2g4c-8fpm-c46v. This link is maintained to preserve external references.\n\n## Original Description\nVersions of the package web3-utils before 4.2.1 are vulnerable to Prototype Pollution via the utility functions format and mergeDeep, due to insecure recursive merge.\nAn attacker can manipulate an object\u0027s prototype, potentially leading to the alteration of the behavior of all objects inheriting from the affected prototype by passing specially crafted input to these functions.",
"id": "GHSA-87qp-7cw8-8q9c",
"modified": "2024-03-27T21:57:36Z",
"published": "2024-03-25T06:30:24Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2024-21505"
},
{
"type": "WEB",
"url": "https://github.com/web3/web3.js/commit/8ed041c6635d807b3da8960ad49e125e3d1b0e80"
},
{
"type": "PACKAGE",
"url": "https://github.com/web3/web3.js"
},
{
"type": "WEB",
"url": "https://security.snyk.io/vuln/SNYK-JS-WEB3UTILS-6229337"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H",
"type": "CVSS_V3"
}
],
"summary": "Duplicate Advisory: web3-utils Prototype Pollution vulnerability",
"withdrawn": "2024-03-27T21:57:36Z"
}
GHSA-88VR-HJQX-57QH
Vulnerability from github – Published: 2024-07-01 15:32 – Updated: 2024-07-03 20:04adolph_dudu ratio-swiper v0.0.2 was discovered to contain a prototype pollution via the function extendDefaults. This vulnerability allows attackers to execute arbitrary code or cause a Denial of Service (DoS) via injecting arbitrary properties.
{
"affected": [
{
"package": {
"ecosystem": "npm",
"name": "@adolph_dudu/ratio-swiper"
},
"versions": [
"0.0.2"
]
}
],
"aliases": [
"CVE-2024-38997"
],
"database_specific": {
"cwe_ids": [
"CWE-1321"
],
"github_reviewed": true,
"github_reviewed_at": "2024-07-01T22:34:44Z",
"nvd_published_at": "2024-07-01T13:15:05Z",
"severity": "MODERATE"
},
"details": "adolph_dudu ratio-swiper v0.0.2 was discovered to contain a prototype pollution via the function extendDefaults. This vulnerability allows attackers to execute arbitrary code or cause a Denial of Service (DoS) via injecting arbitrary properties.",
"id": "GHSA-88vr-hjqx-57qh",
"modified": "2024-07-03T20:04:00Z",
"published": "2024-07-01T15:32:17Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2024-38997"
},
{
"type": "WEB",
"url": "https://gist.github.com/mestrtee/840f5d160aab4151bd0451cfb822e6b5"
},
{
"type": "PACKAGE",
"url": "https://github.com/Adophlidu/swiper"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N",
"type": "CVSS_V3"
}
],
"summary": "adolph_dudu ratio-swiper was discovered to contain a prototype pollution via the function extendDefaults"
}
GHSA-896R-F27R-55MW
Vulnerability from github – Published: 2021-11-19 20:16 – Updated: 2025-01-17 21:31json-schema before version 0.4.0 is vulnerable to Improperly Controlled Modification of Object Prototype Attributes ('Prototype Pollution').
{
"affected": [
{
"package": {
"ecosystem": "npm",
"name": "json-schema"
},
"ranges": [
{
"events": [
{
"introduced": "0"
},
{
"fixed": "0.4.0"
}
],
"type": "ECOSYSTEM"
}
]
}
],
"aliases": [
"CVE-2021-3918"
],
"database_specific": {
"cwe_ids": [
"CWE-1321",
"CWE-915"
],
"github_reviewed": true,
"github_reviewed_at": "2021-11-15T22:44:27Z",
"nvd_published_at": "2021-11-13T09:15:00Z",
"severity": "CRITICAL"
},
"details": "json-schema before version 0.4.0 is vulnerable to Improperly Controlled Modification of Object Prototype Attributes (\u0027Prototype Pollution\u0027).",
"id": "GHSA-896r-f27r-55mw",
"modified": "2025-01-17T21:31:38Z",
"published": "2021-11-19T20:16:17Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2021-3918"
},
{
"type": "WEB",
"url": "https://github.com/kriszyp/json-schema/commit/22f146111f541d9737e832823699ad3528ca7741"
},
{
"type": "WEB",
"url": "https://github.com/kriszyp/json-schema/commit/b62f1da1ff5442f23443d6be6a92d00e65cba93a"
},
{
"type": "WEB",
"url": "https://github.com/kriszyp/json-schema/commit/f6f6a3b02d667aa4ba2d5d50cc19208c4462abfa"
},
{
"type": "PACKAGE",
"url": "https://github.com/kriszyp/json-schema"
},
{
"type": "WEB",
"url": "https://huntr.dev/bounties/bb6ccd63-f505-4e3a-b55f-cd2662c261a9"
},
{
"type": "WEB",
"url": "https://lists.debian.org/debian-lts-announce/2022/12/msg00013.html"
},
{
"type": "WEB",
"url": "https://security.netapp.com/advisory/ntap-20250117-0004"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H",
"type": "CVSS_V3"
}
],
"summary": "json-schema is vulnerable to Prototype Pollution"
}
GHSA-897M-RJF5-JP39
Vulnerability from github – Published: 2022-01-06 20:35 – Updated: 2021-03-24 23:59The package copy-props before 2.0.5 are vulnerable to Prototype Pollution via the main functionality.
{
"affected": [
{
"package": {
"ecosystem": "npm",
"name": "copy-props"
},
"ranges": [
{
"events": [
{
"introduced": "0"
},
{
"fixed": "2.0.5"
}
],
"type": "ECOSYSTEM"
}
]
}
],
"aliases": [
"CVE-2020-28503"
],
"database_specific": {
"cwe_ids": [
"CWE-1321"
],
"github_reviewed": true,
"github_reviewed_at": "2021-03-24T23:59:08Z",
"nvd_published_at": "2021-03-23T10:15:00Z",
"severity": "HIGH"
},
"details": "The package copy-props before 2.0.5 are vulnerable to Prototype Pollution via the main functionality.",
"id": "GHSA-897m-rjf5-jp39",
"modified": "2021-03-24T23:59:08Z",
"published": "2022-01-06T20:35:05Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2020-28503"
},
{
"type": "WEB",
"url": "https://github.com/gulpjs/copy-props/pull/7"
},
{
"type": "WEB",
"url": "https://github.com/gulpjs/copy-props/commit/2c738f5c52cfb384b43d977a56a3ab7ce465df9b"
},
{
"type": "WEB",
"url": "https://snyk.io/vuln/SNYK-JAVA-ORGWEBJARSNPM-1088047"
},
{
"type": "WEB",
"url": "https://snyk.io/vuln/SNYK-JS-COPYPROPS-1082870"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:L",
"type": "CVSS_V3"
}
],
"summary": "Prototype Pollution in copy-props"
}
Mitigation
By freezing the object prototype first (for example, Object.freeze(Object.prototype)), modification of the prototype becomes impossible.
Mitigation
By blocking modifications of attributes that resolve to object prototype, such as proto or prototype, this weakness can be mitigated.
Mitigation
Strategy: Input Validation
When handling untrusted objects, validating using a schema can be used.
Mitigation
By using an object without prototypes (via Object.create(null) ), adding object prototype attributes by accessing the prototype via the special attributes becomes impossible, mitigating this weakness.
Mitigation
Map can be used instead of objects in most cases. If Map methods are used instead of object attributes, it is not possible to access the object prototype or modify it.
CAPEC-1: Accessing Functionality Not Properly Constrained by ACLs
In applications, particularly web applications, access to functionality is mitigated by an authorization framework. This framework maps Access Control Lists (ACLs) to elements of the application's functionality; particularly URL's for web apps. In the case that the administrator failed to specify an ACL for a particular element, an attacker may be able to access it with impunity. An attacker with the ability to access functionality not properly constrained by ACLs can obtain sensitive information and possibly compromise the entire application. Such an attacker can access resources that must be available only to users at a higher privilege level, can access management sections of the application, or can run queries for data that they otherwise not supposed to.
CAPEC-180: Exploiting Incorrectly Configured Access Control Security Levels
An attacker exploits a weakness in the configuration of access controls and is able to bypass the intended protection that these measures guard against and thereby obtain unauthorized access to the system or network. Sensitive functionality should always be protected with access controls. However configuring all but the most trivial access control systems can be very complicated and there are many opportunities for mistakes. If an attacker can learn of incorrectly configured access security settings, they may be able to exploit this in an attack.
CAPEC-77: Manipulating User-Controlled Variables
This attack targets user controlled variables (DEBUG=1, PHP Globals, and So Forth). An adversary can override variables leveraging user-supplied, untrusted query variables directly used on the application server without any data sanitization. In extreme cases, the adversary can change variables controlling the business logic of the application. For instance, in languages like PHP, a number of poorly set default configurations may allow the user to override variables.