CVE-2021-26423 (GCVE-0-2021-26423)
Vulnerability from cvelistv5 – Published: 2021-08-12 18:11 – Updated: 2026-08-10 15:09
VLAI
EPSS
VEX
Title
.NET Core and Visual Studio Denial of Service Vulnerability
Summary
.NET Core and Visual Studio Denial of Service Vulnerability
Severity
SSVC
Exploitation: none
Automatable: yes
Technical Impact: partial
CISA Coordinator · CISA-ADP (v2.0.3)
Decision recorded 2025-06-04 13:28 UTC
CWE
- Denial of Service
- CWE-noinfo Not enough information
Assigner
References
2 references
| URL | Tags |
|---|---|
| https://msrc.microsoft.com/update-guide/vulnerabi… | vendor-advisorypatch |
| https://portal.msrc.microsoft.com/en-US/security-… | x_refsource_MISCx_transferred |
Impacted products
11 products
| Vendor | Product | Version | |
|---|---|---|---|
| Microsoft | .NET 5.0 |
Affected:
5.0.0 , < 5.0.9
(custom)
|
|
| Microsoft | .NET Core 2.1 |
Affected:
2.1 , < 2.1.30
(custom)
|
|
| Microsoft | .NET Core 3.1 |
Affected:
3.1 , < 3.1.18
(custom)
|
|
| Microsoft | Microsoft Visual Studio 2017 version 15.9 (includes 15.0 - 15.8) |
Affected:
15.9.0 , < 15.9.38
(custom)
|
|
| Microsoft | Microsoft Visual Studio 2019 version 16.10 (includes 16.0 - 16.9) |
Affected:
16.10.0 , < 16.10.5
(custom)
|
|
| Microsoft | Microsoft Visual Studio 2019 version 16.4 (includes 16.0 - 16.3) |
Affected:
16.0 , < 16.4.25
(custom)
|
|
| Microsoft | Microsoft Visual Studio 2019 version 16.7 (includes 16.0 – 16.6) |
Affected:
16.0.0 , < 16.7.18
(custom)
|
|
| Microsoft | Microsoft Visual Studio 2019 version 16.9 (includes 16.0 - 16.8) |
Affected:
15.0.0 , < 16.9.10
(custom)
|
|
| Microsoft | PowerShell Core 7.0 |
Affected:
7.0.0 , < 7.0.7
(custom)
|
|
| Microsoft | PowerShell Core 7.1 |
Affected:
7.1.0 , < 7.1.4
(custom)
|
|
| Microsoft | Visual Studio 2019 for Mac version 8.10 |
Affected:
8.1.0 , < 8.10.7
(custom)
|
Date Public
2021-08-10 14:00
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{
"lessThan": "3.1.18",
"status": "affected",
"version": "3.1",
"versionType": "custom"
}
]
},
{
"product": "Microsoft Visual Studio 2017 version 15.9 (includes 15.0 - 15.8)",
"vendor": "Microsoft",
"versions": [
{
"lessThan": "15.9.38",
"status": "affected",
"version": "15.9.0",
"versionType": "custom"
}
]
},
{
"product": "Microsoft Visual Studio 2019 version 16.10 (includes 16.0 - 16.9)",
"vendor": "Microsoft",
"versions": [
{
"lessThan": "16.10.5",
"status": "affected",
"version": "16.10.0",
"versionType": "custom"
}
]
},
{
"product": "Microsoft Visual Studio 2019 version 16.4 (includes 16.0 - 16.3)",
"vendor": "Microsoft",
"versions": [
{
"lessThan": "16.4.25",
"status": "affected",
"version": "16.0",
"versionType": "custom"
}
]
},
{
"product": "Microsoft Visual Studio 2019 version 16.7 (includes 16.0 \u2013 16.6)",
"vendor": "Microsoft",
"versions": [
{
"lessThan": "16.7.18",
"status": "affected",
"version": "16.0.0",
"versionType": "custom"
}
]
},
{
"product": "Microsoft Visual Studio 2019 version 16.9 (includes 16.0 - 16.8)",
"vendor": "Microsoft",
"versions": [
{
"lessThan": "16.9.10",
"status": "affected",
"version": "15.0.0",
"versionType": "custom"
}
]
},
{
"product": "PowerShell Core 7.0",
"vendor": "Microsoft",
"versions": [
{
"lessThan": "7.0.7",
"status": "affected",
"version": "7.0.0",
"versionType": "custom"
}
]
},
{
"product": "PowerShell Core 7.1",
"vendor": "Microsoft",
"versions": [
{
"lessThan": "7.1.4",
"status": "affected",
"version": "7.1.0",
"versionType": "custom"
}
]
},
{
"product": "Visual Studio 2019 for Mac version 8.10",
"vendor": "Microsoft",
"versions": [
{
"lessThan": "8.10.7",
"status": "affected",
"version": "8.1.0",
"versionType": "custom"
}
]
}
],
"cpeApplicability": [
{
"nodes": [
{
"cpeMatch": [
{
"criteria": "cpe:2.3:a:microsoft:visual_studio_2017:*:*:*:*:*:*:*:*",
"versionEndExcluding": "15.9.38",
"versionStartIncluding": "15.9.0",
"vulnerable": true
},
{
"criteria": "cpe:2.3:a:microsoft:visual_studio_2019:*:*:*:*:*:*:*:*",
"versionEndExcluding": "16.4.25",
"versionStartIncluding": "16.0",
"vulnerable": true
},
{
"criteria": "cpe:2.3:a:microsoft:visual_studio_2019:*:*:*:*:*:*:*:*",
"versionEndExcluding": "16.7.18",
"versionStartIncluding": "16.0.0",
"vulnerable": true
},
{
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"vulnerable": true
},
{
"criteria": "cpe:2.3:a:microsoft:visual_studio_2019:*:*:*:*:*:*:*:*",
"versionEndExcluding": "16.10.5",
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},
{
"criteria": "cpe:2.3:a:microsoft:visual_studio_2019:*:*:*:*:*:macos:*:*",
"versionEndExcluding": "8.10.7",
"versionStartIncluding": "8.1.0",
"vulnerable": true
},
{
"criteria": "cpe:2.3:a:microsoft:.net_core:*:*:*:*:*:*:*:*",
"versionEndExcluding": "2.1.30",
"versionStartIncluding": "2.1",
"vulnerable": true
},
{
"criteria": "cpe:2.3:a:microsoft:.net_core:*:*:*:*:*:*:*:*",
"versionEndExcluding": "3.1.18",
"versionStartIncluding": "3.1",
"vulnerable": true
},
{
"criteria": "cpe:2.3:a:microsoft:.net:*:*:*:*:*:*:*:*",
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"versionStartIncluding": "5.0.0",
"vulnerable": true
},
{
"criteria": "cpe:2.3:a:microsoft:powershell_core:*:*:*:*:*:*:*:*",
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},
{
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"versionStartIncluding": "7.0.0",
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}
],
"negate": false,
"operator": "OR"
}
]
}
],
"datePublic": "2021-08-10T14:00:00.000Z",
"descriptions": [
{
"lang": "en-US",
"value": ".NET Core and Visual Studio Denial of Service Vulnerability"
}
],
"metrics": [
{
"cvssV3_1": {
"baseScore": 7.5,
"baseSeverity": "HIGH",
"vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H/E:U/RL:O/RC:C",
"version": "3.1"
},
"format": "CVSS",
"scenarios": [
{
"lang": "en-US",
"value": "GENERAL"
}
]
}
],
"problemTypes": [
{
"descriptions": [
{
"description": "Denial of Service",
"lang": "en-US",
"type": "Impact"
}
]
}
],
"providerMetadata": {
"dateUpdated": "2026-08-10T15:09:59.739Z",
"orgId": "f38d906d-7342-40ea-92c1-6c4a2c6478c8",
"shortName": "microsoft"
},
"references": [
{
"name": ".NET Core and Visual Studio Denial of Service Vulnerability",
"tags": [
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"patch"
],
"url": "https://msrc.microsoft.com/update-guide/vulnerability/CVE-2021-26423"
}
],
"title": ".NET Core and Visual Studio Denial of Service Vulnerability"
}
},
"cveMetadata": {
"assignerOrgId": "f38d906d-7342-40ea-92c1-6c4a2c6478c8",
"assignerShortName": "microsoft",
"cveId": "CVE-2021-26423",
"datePublished": "2021-08-12T18:11:31.000Z",
"dateReserved": "2021-01-29T00:00:00.000Z",
"dateUpdated": "2026-08-10T15:09:59.739Z",
"state": "PUBLISHED"
},
"dataType": "CVE_RECORD",
"dataVersion": "5.2"
}
}
}
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Experimental. This forecast is provided for visualization only and may change without notice. Do not use it for operational decisions.
Forecast uses a logistic model when the trend is rising, or an exponential decay model when the trend is falling. Fitted via linearized least squares.
Sightings
| Author | Source | Type | Date | Other |
|---|
Nomenclature
- Seen: The vulnerability was mentioned, discussed, or observed by the user.
- Confirmed: The vulnerability has been validated from an analyst's perspective.
- Published Proof of Concept: A public proof of concept is available for this vulnerability.
- Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
- Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
- Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
- Not confirmed: The user expressed doubt about the validity of the vulnerability.
- Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.
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The MITRE ATT&CK techniques below are AI-generated suggestions, inferred from the description of the
vulnerability by the CIRCL/vulnerability-attack-technique-classification-roberta-base
model, served locally by ML-Gateway.
They have not been verified by an analyst and are provided for guidance only.
The approach is described in our paper Mapping CVEs to MITRE ATT&CK Techniques: A Curated Gold-Set Classifier and the Limits of LLM-Assisted Label Expansion.
Browse all ATT&CK techniques and the vulnerabilities related to each.
The approach is described in our paper Mapping CVEs to MITRE ATT&CK Techniques: A Curated Gold-Set Classifier and the Limits of LLM-Assisted Label Expansion.
Browse all ATT&CK techniques and the vulnerabilities related to each.
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Related by attack behaviour
Vulnerabilities whose description is nearest to this one in the vector space of the CIRCL/vulnerability-attack-technique-biencoder model. This is a similarity search over the bi-encoder space (plain cosine), not a classification, and it has no measured accuracy.
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