Answer in brief
CVE-2026-23666 records a High severity (CVSS 7.5) vulnerability in .NET Framework Denial of Service Vulnerability. The current sources do not mark it as known exploited. The current feed maps Microsoft/Microsoft .NET Framework 3.5 (generic), Microsoft/Microsoft .NET Framework 3.5 AND 4.7.2 (generic), Microsoft/Microsoft .NET Framework 3.5 AND 4.8 (generic), Microsoft/Microsoft .NET Framework 3.5 AND 4.8.1 (generic) and additional mapped packages. Check affected ranges and fixed versions before updating.
Analysis pending evidence review
HOL Guard separates source facts from reviewed analysis. See the methodology.
CVSS is 7.5. The current sources do not mark it as known exploited. Treat this as a source-backed prioritization signal, not a statement about your environment.
Analysis status
Analysis pending evidence review
Factual feed record only; HOL analysis is not approved for indexing. Read the methodology.
The current feed maps Microsoft/Microsoft .NET Framework 3.5 (generic), Microsoft/Microsoft .NET Framework 3.5 AND 4.7.2 (generic), Microsoft/Microsoft .NET Framework 3.5 AND 4.8 (generic), Microsoft/Microsoft .NET Framework 3.5 AND 4.8.1 (generic) and additional mapped packages. Check affected ranges and fixed versions before updating.
| Package | Affected range | Fixed version |
|---|---|---|
| Microsoft/Microsoft .NET Framework 3.5generic | >=3.5.0 <2.0.50727.8982 & 3.0.30729.8976 | 2.0.50727.8982 & 3.0.30729.8976 |
| Microsoft/Microsoft .NET Framework 3.5 AND 4.7.2generic | >=4.7.0 <2.0.50727.9068 & 3.0.30729.9065 & 4.7.4141.0 | 2.0.50727.9068 & 3.0.30729.9065 & 4.7.4141.0 |
| Microsoft/Microsoft .NET Framework 3.5 AND 4.8generic | >=4.8.0 <2.0.50727.9068 & 3.0.30729.9065 & 4.8.4801.0 | 2.0.50727.9068 & 3.0.30729.9065 & 4.8.4801.0 |
| Microsoft/Microsoft .NET Framework 3.5 AND 4.8.1generic | >=4.8.1 <2.0.50727.9181 & 3.0.30729.9165 & 4.8.9332.0 | 2.0.50727.9181 & 3.0.30729.9165 & 4.8.9332.0 |
| Microsoft/Microsoft .NET Framework 4.6.2/4.7/4.7.1/4.7.2generic | >=4.7.0 <4.8.4801.0 | 4.8.4801.0 |
| Microsoft/Microsoft .NET Framework 4.8generic | >=4.8.0 <4.8.4801.0 | 4.8.4801.0 |
Published upstream
Apr 14, 2026
Evidence: source:cvelist:source_dates:source-dates:recordSource modified
Jul 15, 2026
Evidence: source:cvelist:source_dates:source-dates:recordFirst seen by HOL
Jul 15, 2026
A flaw was found in .NET Framework. An unauthorized attacker can exploit a race condition, which is a concurrent execution using shared resources with improper synchronization, to deny service over a network. This vulnerability can lead to a Denial of Service (DoS) for affected systems.
Quoted source text, attributed separately from HOL analysis.
Answer in brief
CVE-2026-23666 records a High severity (CVSS 7.5) vulnerability in .NET Framework Denial of Service Vulnerability. The current sources do not mark it as known exploited. The current feed maps Microsoft/Microsoft .NET Framework 3.5 (generic), Microsoft/Microsoft .NET Framework 3.5 AND 4.7.2 (generic), Microsoft/Microsoft .NET Framework 3.5 AND 4.8 (generic), Microsoft/Microsoft .NET Framework 3.5 AND 4.8.1 (generic) and additional mapped packages. Check affected ranges and fixed versions before updating.
Analysis pending evidence review
HOL Guard separates source facts from reviewed analysis. See the methodology.
CVSS is 7.5. The current sources do not mark it as known exploited. Treat this as a source-backed prioritization signal, not a statement about your environment.
Analysis status
Analysis pending evidence review
Factual feed record only; HOL analysis is not approved for indexing. Read the methodology.
The current feed maps Microsoft/Microsoft .NET Framework 3.5 (generic), Microsoft/Microsoft .NET Framework 3.5 AND 4.7.2 (generic), Microsoft/Microsoft .NET Framework 3.5 AND 4.8 (generic), Microsoft/Microsoft .NET Framework 3.5 AND 4.8.1 (generic) and additional mapped packages. Check affected ranges and fixed versions before updating.
| Package | Affected range | Fixed version |
|---|---|---|
| Microsoft/Microsoft .NET Framework 3.5generic | >=3.5.0 <2.0.50727.8982 & 3.0.30729.8976 | 2.0.50727.8982 & 3.0.30729.8976 |
| Microsoft/Microsoft .NET Framework 3.5 AND 4.7.2generic | >=4.7.0 <2.0.50727.9068 & 3.0.30729.9065 & 4.7.4141.0 | 2.0.50727.9068 & 3.0.30729.9065 & 4.7.4141.0 |
| Microsoft/Microsoft .NET Framework 3.5 AND 4.8generic | >=4.8.0 <2.0.50727.9068 & 3.0.30729.9065 & 4.8.4801.0 | 2.0.50727.9068 & 3.0.30729.9065 & 4.8.4801.0 |
| Microsoft/Microsoft .NET Framework 3.5 AND 4.8.1generic | >=4.8.1 <2.0.50727.9181 & 3.0.30729.9165 & 4.8.9332.0 | 2.0.50727.9181 & 3.0.30729.9165 & 4.8.9332.0 |
| Microsoft/Microsoft .NET Framework 4.6.2/4.7/4.7.1/4.7.2generic | >=4.7.0 <4.8.4801.0 | 4.8.4801.0 |
| Microsoft/Microsoft .NET Framework 4.8generic | >=4.8.0 <4.8.4801.0 | 4.8.4801.0 |
Published upstream
Apr 14, 2026
Evidence: source:cvelist:source_dates:source-dates:recordSource modified
Jul 15, 2026
Evidence: source:cvelist:source_dates:source-dates:recordFirst seen by HOL
Jul 15, 2026
A flaw was found in .NET Framework. An unauthorized attacker can exploit a race condition, which is a concurrent execution using shared resources with improper synchronization, to deny service over a network. This vulnerability can lead to a Denial of Service (DoS) for affected systems.
Quoted source text, attributed separately from HOL analysis.