Common Weakness Enumeration
CWE-621
Weakness AllowedVariable Extraction Error
Abstraction: Variant · Status: Incomplete
The product uses external input to determine the names of variables into which information is extracted, without verifying that the names of the specified variables are valid.
Mapping guidance
This CWE entry is at the Variant 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.
Modes of introduction
Implementation
Notes
Research Gap
Probably under-reported for PHP. Seems under-studied for other interpreted languages.
Content history
Submission: CWE Content Team
· MITRE
· 2007-05-07
· CWE Draft 6
Modification: Eric Dalci
· Cigital
· 2008-07-01
· CWE 1.0
updated Time_of_Introduction
Modification: CWE Content Team
· MITRE
· 2008-09-08
· CWE 1.0
updated Description, Relationships, Observed_Example, Other_Notes, Weakness_Ordinalities
Modification: CWE Content Team
· MITRE
· 2008-10-14
· CWE 1.0.1
updated Description
Modification: CWE Content Team
· MITRE
· 2011-06-01
· CWE 1.13
updated Common_Consequences
Modification: CWE Content Team
· MITRE
· 2012-05-11
· CWE 2.2
updated Common_Consequences, Demonstrative_Examples, Relationships
Modification: CWE Content Team
· MITRE
· 2012-10-30
· CWE 2.3
updated Potential_Mitigations
Modification: CWE Content Team
· MITRE
· 2013-02-21
· CWE 2.4
updated Demonstrative_Examples, Relationships
Modification: CWE Content Team
· MITRE
· 2014-06-23
· CWE 2.7
updated Description, Other_Notes
Modification: CWE Content Team
· MITRE
· 2014-07-30
· CWE 2.8
updated Relationships, Taxonomy_Mappings
Modification: CWE Content Team
· MITRE
· 2020-02-24
· CWE 4.0
updated Relationships
Modification: CWE Content Team
· MITRE
· 2020-06-25
· CWE 4.1
updated Potential_Mitigations
Modification: CWE Content Team
· MITRE
· 2022-04-28
· CWE 4.7
updated Research_Gaps
Modification: CWE Content Team
· MITRE
· 2023-04-27
· CWE 4.11
updated Relationships, Type
Modification: CWE Content Team
· MITRE
· 2023-06-29
· CWE 4.12
updated Mapping_Notes
Modification: CWE Content Team
· MITRE
· 2023-10-26
· CWE 4.13
updated Observed_Examples
Modification: CWE Content Team
· MITRE
· 2026-04-30
· CWE 4.20
updated Potential_Mitigations
Modification: CWE Content Team
· MITRE
· 2026-10-28
· CWE 5.0
updated Applicable_Platforms, Common_Consequences, Demonstrative_Examples, Description
3 vulnerabilities reference this CWE, most recent first.
CVE-2018-6334 (GCVE-0-2018-6334)
Vulnerability from cvelistv5 – Published: 2018-12-31 20:00 – Updated: 2025-05-06 16:48
VLAI
EPSS
VEX
Summary
Multipart-file uploads call variables to be improperly registered in the global scope. In cases where variables are not declared explicitly before being used this can lead to unexpected behavior. This affects all supported versions of HHVM prior to the patch (3.25.1, 3.24.5, and 3.21.9 and below).
Severity
9.8 (Critical)
SSVC
Exploitation: none
Automatable: yes
Technical Impact: total
CISA Coordinator · CISA-ADP (v2.0.3)
Decision recorded 2025-05-06 16:40 UTC
CWE
- CWE-621 - Variable Extraction Error (CWE-621)
References
2 references
| URL | Tags |
|---|---|
| https://github.com/facebook/hhvm/commit/6937de554… | x_refsource_MISC |
| https://hhvm.com/blog/2018/03/30/hhvm-3.25.2.html | x_refsource_MISC |
Impacted products
Date Public
2018-12-31 00:00
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GHSA-V7MG-WG5H-PCX8
Vulnerability from github – Published: 2022-05-13 01:32 – Updated: 2022-05-13 01:32
VLAI
Details
Multipart-file uploads call variables to be improperly registered in the global scope. In cases where variables are not declared explicitly before being used this can lead to unexpected behavior. This affects all supported versions of HHVM prior to the patch (3.25.1, 3.24.5, and 3.21.9 and below).
Severity
9.8 (Critical)
{
"affected": [],
"aliases": [
"CVE-2018-6334"
],
"database_specific": {
"cwe_ids": [
"CWE-20",
"CWE-621"
],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2018-12-31T19:29:00Z",
"severity": "CRITICAL"
},
"details": "Multipart-file uploads call variables to be improperly registered in the global scope. In cases where variables are not declared explicitly before being used this can lead to unexpected behavior. This affects all supported versions of HHVM prior to the patch (3.25.1, 3.24.5, and 3.21.9 and below).",
"id": "GHSA-v7mg-wg5h-pcx8",
"modified": "2022-05-13T01:32:03Z",
"published": "2022-05-13T01:32:03Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2018-6334"
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"url": "https://github.com/facebook/hhvm/commit/6937de5544c3eead3466b75020d8382080ed0cff"
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{
"type": "WEB",
"url": "https://hhvm.com/blog/2018/03/30/hhvm-3.25.2.html"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H",
"type": "CVSS_V3"
}
]
}
GHSA-X962-W72P-MV7Q
Vulnerability from github – Published: 2022-05-17 05:07 – Updated: 2023-08-28 23:52
VLAI
Summary
phpMyAdmin Global variables scope injection vulnerability
Details
import.php in phpMyAdmin 4.x before 4.0.4.1 does not properly restrict the ability of input data to specify a file format, which allows remote authenticated users to modify the GLOBALS superglobal array, and consequently change the configuration, via a crafted request.
Severity
5.4 (Medium)
{
"affected": [
{
"package": {
"ecosystem": "Packagist",
"name": "phpmyadmin/phpmyadmin"
},
"ranges": [
{
"events": [
{
"introduced": "4.0"
},
{
"fixed": "4.0.4.1"
}
],
"type": "ECOSYSTEM"
}
]
}
],
"aliases": [
"CVE-2013-4729"
],
"database_specific": {
"cwe_ids": [
"CWE-621"
],
"github_reviewed": true,
"github_reviewed_at": "2023-08-28T23:52:58Z",
"nvd_published_at": "2013-07-04T14:33:00Z",
"severity": "MODERATE"
},
"details": "import.php in phpMyAdmin 4.x before 4.0.4.1 does not properly restrict the ability of input data to specify a file format, which allows remote authenticated users to modify the GLOBALS superglobal array, and consequently change the configuration, via a crafted request.",
"id": "GHSA-x962-w72p-mv7q",
"modified": "2023-08-28T23:52:58Z",
"published": "2022-05-17T05:07:49Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2013-4729"
},
{
"type": "WEB",
"url": "https://github.com/phpmyadmin/phpmyadmin/commit/012464268420e53a9cd81cbb4a43988d70393c36"
},
{
"type": "PACKAGE",
"url": "https://github.com/phpmyadmin/phpmyadmin"
},
{
"type": "WEB",
"url": "http://www.phpmyadmin.net/home_page/security/PMASA-2013-7.php"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:L/A:L",
"type": "CVSS_V3"
}
],
"summary": "phpMyAdmin Global variables scope injection vulnerability"
}
Mitigation
Implementation
Strategy: Input Validation
Use allowlists of variable names that can be extracted.
Mitigation
Implementation
Strategy: Refactoring
Consider refactoring your code to avoid extraction routines altogether.
Mitigation
Implementation
In PHP, call extract() with options such as EXTR_SKIP and EXTR_PREFIX_ALL; call import_request_variables() with a prefix argument. Note that these capabilities are not present in all PHP versions.
No CAPEC attack patterns related to this CWE.