CVE-2026-32226: .NET Framework Denial of Service Vulnerability

CVE-2026-32226 is a denial of service vulnerability in .NET Framework, rated Important by Microsoft, with a CVSS 3.1 base score of 5.9 (Medium). An attacker can exploit it remotely over the network, without any privileges and without user interaction. Microsoft has not reported exploitation in the wild and rates exploitation as less likely. The EPSS model estimates a 0.54% probability of exploitation activity in the next 30 days, higher than 46% of all scored vulnerabilities. Microsoft released the fix on 14 April 2026 in the April 2026 Patch Tuesday, delivered through 18 security updates (KB5082426, KB5082424, KB5082411, KB5082403 and more). It affects 55 products in 1 product family (Developer Tools).

Key facts

CVE ID: CVE-2026-32226
Severity: Medium CVSS 5.9
Microsoft severity: Important
Impact: Denial of Service
Exploited in the wild: No
Publicly disclosed: No
Exploitation likelihood: Less Likely
Weakness: CWE-362
EPSS: 0.54% (percentile 46%)
CISA KEV: Not listed
Released: 14 April 2026
Last updated: 11 May 2026
Patch Tuesday: April 2026 Patch Tuesday
Product families: Developer Tools

CVSS score and vector

Microsoft scores CVE-2026-32226 at 5.9 (temporal 5.2) using CVSS 3.1. Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H/E:U/RL:O/RC:C

Metric	Value
Attack vector	Network
Attack complexity	High
Privileges required	None
User interaction	None
Scope	Unchanged
Confidentiality impact	None
Integrity impact	None
Availability impact	High
Exploit code maturity	Unproven
Remediation level	Official fix
Report confidence	Confirmed

Description

Concurrent execution using shared resource with improper synchronization ('race condition') in .NET Framework allows an unauthorized attacker to deny service over a network.

Frequently asked questions (Microsoft)

According to the CVSS metric, the attack complexity is high (AC:H). What does that mean for this vulnerability?

Successful exploitation of this vulnerability requires an attacker to win a race condition.

Affected products (55)

Developer Tools

Product	Security update	Type	Fixed build	Restart
Microsoft .NET Framework 4.8 on Windows 10 Version 22H2 for x64-based Systems	KB5082426	Security Update	2.0.50727.9181 & 3.0.30729.9165 & 4.8.4801.0	Maybe
Microsoft .NET Framework 4.8 on Windows 11 Version 22H2 for x64-based Systems	KB5082424	Security Update	2.0.50727.9181 & 3.0.30729.9165 & 4.8.9332.0	Maybe
Microsoft .NET Framework 4.8 on Windows 10 Version 1607 for x64-based Systems	KB5082411	Security Update	4.8.4801.0	Maybe
Microsoft .NET Framework 4.8 on Windows Server 2012 R2 (Server Core installation)	KB5082411	Security Update	4.8.4801.0	Maybe
Microsoft .NET Framework 4.8 on Windows Server 2012 (Server Core installation)	KB5082403	Security Update	4.8.4801.0	Maybe
Microsoft .NET Framework 4.8 on Windows Server 2012 R2	KB5082404	Security Update	4.8.4801.0	Maybe
Microsoft .NET Framework 3.5 AND 4.8 on Windows 10 Version 1809 for x64-based Systems	KB5082414	Security Update	2.0.50727.9068 & 3.0.30729.9065 & 4.8.4801.0	Maybe
Microsoft .NET Framework 3.5 AND 4.8 on Windows 10 Version 1809 for 32-bit Systems	KB5082414	Security Update	2.0.50727.9068 & 3.0.30729.9065 & 4.8.4801.0	Maybe
Microsoft .NET Framework 3.5 AND 4.8 on Windows 10 Version 1809 for ARM64-based Systems	KB5082414	Security Update	2.0.50727.9068 & 3.0.30729.9065 & 4.8.4801.0	Maybe
Microsoft .NET Framework 3.5 AND 4.8 on Windows Server, version 20H2 (Server Core Installation)	KB5082426	Security Update	2.0.50727.9181 & 3.0.30729.9165 & 4.8.4801.0	Maybe
Microsoft .NET Framework 3.5 AND 4.8 on Windows 11 version 21H2 for x64-based Systems	KB5082426	Security Update	2.0.50727.9181 & 3.0.30729.9165 & 4.8.4801.0	Maybe
Microsoft .NET Framework 3.5 AND 4.8 on Windows 10 Version 21H2 for ARM64-based Systems	KB5082419	Security Update	2.0.50727.9181 & 3.0.30729.9165 & 4.8.9332.0	Maybe
Microsoft .NET Framework 3.5 AND 4.8 on Windows 10 Version 21H2 for 32-bit Systems	KB5082419	Security Update	2.0.50727.9181 & 3.0.30729.9165 & 4.8.9332.0	Maybe
Microsoft .NET Framework 3.5 AND 4.8 on Windows 10 Version 21H2 for x64-based Systems	KB5082419	Security Update	2.0.50727.9181 & 3.0.30729.9165 & 4.8.9332.0	Maybe
Microsoft .NET Framework 3.5 AND 4.7.2 on Windows 10 Version 1809 for x64-based Systems	KB5082413	Security Update	2.0.50727.9068 & 3.0.30729.9065 & 4.7.4141.0	Maybe
Microsoft .NET Framework 3.5 AND 4.7.2 on Windows 10 Version 1809 for ARM64-based Systems	KB5082413	Security Update	2.0.50727.9068 & 3.0.30729.9065 & 4.7.4141.0	Maybe
Microsoft .NET Framework 4.7.2 on Windows 10 Version 1809 for 32-bit Systems	KB5082413	Security Update	2.0.50727.9068 & 3.0.30729.9065 & 4.7.4141.0	Maybe
Microsoft .NET Framework 4.7.2 on Windows 10 Version 1809 for x64-based Systems	KB5082413	Security Update	2.0.50727.9068 & 3.0.30729.9065 & 4.7.4141.0	Maybe
Microsoft .NET Framework 4.7.2 on Windows 10 Version 1809 for ARM64-based Systems	KB5082413	Security Update	2.0.50727.9068 & 3.0.30729.9065 & 4.7.4141.0	Maybe
Microsoft .NET Framework 4.8.1 on Windows Server 2022 (Server Core installation)	KB5082425	Security Update	2.0.50727.9181 & 3.0.30729.9165 & 4.8.9332.0	Maybe
Microsoft .NET Framework 3.5 AND 4.8.1 on Windows 10 Version 21H2 for 32-bit Systems	KB5082419	Security Update	2.0.50727.9181 & 3.0.30729.9165 & 4.8.9332.0	Maybe
Microsoft .NET Framework 3.5 AND 4.8.1 on Windows 10 Version 21H2 for ARM64-based Systems	KB5082419	Security Update	2.0.50727.9181 & 3.0.30729.9165 & 4.8.9332.0	Maybe
Microsoft .NET Framework 3.5 AND 4.8.1 on Windows 10 Version 21H2 for x64-based Systems	KB5082419	Security Update	2.0.50727.9181 & 3.0.30729.9165 & 4.8.9332.0	Maybe
Microsoft .NET Framework 3.5 AND 4.8.1 on Windows 11 Version 22H2 for ARM64-based Systems	KB5082424	Security Update	2.0.50727.9181 & 3.0.30729.9165 & 4.8.9332.0	Maybe
Microsoft .NET Framework 3.5 AND 4.8.1 on Windows 11 Version 22H2 for x64-based Systems	KB5082424	Security Update	2.0.50727.9181 & 3.0.30729.9165 & 4.8.9332.0	Maybe
Microsoft .NET Framework 3.5 AND 4.8.1 on Windows Server 2022, 23H2 Edition (Server Core installation)	KB5082418	Security Update	2.0.50727.9181 & 3.0.30729.9165 & 4.8.9332.0	Maybe
Microsoft .NET Framework 3.5 AND 4.8.1 on Windows 11 Version 23H2 for x64-based Systems	KB5082424	Security Update	2.0.50727.9181 & 3.0.30729.9165 & 4.8.9332.0	Maybe
Microsoft .NET Framework 3.5 AND 4.8.1 on Windows 11 Version 24H2 for ARM64-based Systems	KB5082420	Security Update	2.0.50727.9181 & 3.0.30729.9165 & 4.8.9332.0	Maybe
Microsoft .NET Framework 3.5 AND 4.8.1 on Windows 11 Version 24H2 for x64-based Systems	KB5082420	Security Update	2.0.50727.9181 & 3.0.30729.9165 & 4.8.9332.0	Maybe
Microsoft .NET Framework 3.5 on Windows Server 2012 R2	KB5082406	Security Update	2.0.50727.8982 & 3.0.30729.8976	Maybe
Microsoft .NET Framework 3.5 on Windows Server 2012 R2 (Server Core installation)	KB5082406	Security Update	2.0.50727.8982 & 3.0.30729.8976	Maybe
Microsoft .NET Framework 3.5 AND 4.8.1 on Windows 11 version 26H1 for x64-based Systems	KB5082421	Security Update	2.0.50727.9181 & 3.0.30729.9165 & 4.8.9332.0	Maybe
Microsoft .NET Framework 3.5 AND 4.8.1 on Windows 11 Version 26H1 for ARM64-based Systems	KB5082421	Security Update	2.0.50727.9181 & 3.0.30729.9165 & 4.8.9332.0	Maybe
Microsoft .NET Framework 3.5 AND 4.8 on Windows Server 2022	KB5082427	Security Update	2.0.50727.9181 & 3.0.30729.9165 & 4.8.4801.0	Maybe
Microsoft .NET Framework 3.5 AND 4.8 on Windows Server 2022 (Server Core installation)	KB5082427	Security Update	2.0.50727.9181 & 3.0.30729.9165 & 4.8.4801.0	Maybe
Microsoft .NET Framework 3.5 AND 4.8 on Windows 10 Version 22H2 for x64-based Systems	KB5082426	Security Update	2.0.50727.9181 & 3.0.30729.9165 & 4.8.4801.0	Maybe
Microsoft .NET Framework 3.5 AND 4.8 on Windows 10 Version 22H2 for ARM64-based Systems	KB5082426	Security Update	2.0.50727.9181 & 3.0.30729.9165 & 4.8.4801.0	Maybe
Microsoft .NET Framework 3.5 AND 4.8 on Windows 10 Version 22H2 for 32-bit Systems	KB5082426	Security Update	2.0.50727.9181 & 3.0.30729.9165 & 4.8.4801.0	Maybe
Microsoft .NET Framework 3.5 AND 4.7.2 on Windows 10 Version 1809 for 32-bit Systems	KB5082413	Security Update	2.0.50727.9068 & 3.0.30729.9065 & 4.7.4141.0	Maybe
Microsoft .NET Framework 4.6.2/4.7/4.7.1/4.7.2 on Windows Server 2012 (Server Core installation)	KB5082400	Security Update	4.8.4801.0	Maybe
Microsoft .NET Framework 4.6.2/4.7/4.7.1/4.7.2 on Windows Server 2012	KB5082400	Security Update	4.8.4801.0	Maybe
Microsoft .NET Framework 4.6.2/4.7/4.7.1/4.7.2 on Windows Server 2012 R2 (Server Core installation)	KB5082402	Security Update	4.7.4141.0	Maybe
Microsoft .NET Framework 4.6.2/4.7/4.7.1/4.7.2 on Windows Server 2012 R2	KB5082402	Security Update	4.7.4141.0	Maybe
Microsoft .NET Framework 3.5 AND 4.8.1 on Windows Server 2022	KB5082425	Security Update	2.0.50727.9181 & 3.0.30729.9165 & 4.8.9332.0	Maybe
Microsoft .NET Framework 3.5 AND 4.8.1 on Windows Server 2022 (Server Core installation)	KB5082425	Security Update	2.0.50727.9181 & 3.0.30729.9165 & 4.8.9332.0	Maybe
Microsoft .NET Framework 3.5 AND 4.8.1 on Windows 10 Version 22H2 for x64-based Systems	KB5082419	Security Update	2.0.50727.9181 & 3.0.30729.9165 & 4.8.9332.0	Maybe
Microsoft .NET Framework 3.5 AND 4.8.1 on Windows 10 Version 22H2 for ARM64-based Systems	KB5082419	Security Update	2.0.50727.9181 & 3.0.30729.9165 & 4.8.9332.0	Maybe
Microsoft .NET Framework 3.5 AND 4.8.1 on Windows 10 Version 22H2 for 32-bit Systems	KB5082419	Security Update	2.0.50727.9181 & 3.0.30729.9165 & 4.8.9332.0	Maybe
Microsoft .NET Framework 3.5 AND 4.8.1 on Windows 11 Version 25H2 for ARM64-based Systems	KB5082417	Security Update	2.0.50727.9181 & 3.0.30729.9165 & 4.8.9332.0	Maybe
Microsoft .NET Framework 3.5 AND 4.8.1 on Windows 11 Version 25H2 for x64-based Systems	KB5082417	Security Update	2.0.50727.9181 & 3.0.30729.9165 & 4.8.9332.0	Maybe
Microsoft .NET Framework 3.5 AND 4.8.1 on Windows 11 Version 23H2 for ARM64-based Systems	KB5082424	Security Update	2.0.50727.9181 & 3.0.30729.9165 & 4.8.9332.0	Maybe
Microsoft .NET Framework 3.5 on Windows Server 2012	KB5082398	Security Update	2.0.50727.8982 & 3.0.30729.8976	Maybe
Microsoft .NET Framework 3.5 on Windows Server 2012 (Server Core installation)	KB5082398	Security Update	2.0.50727.8982 & 3.0.30729.8976	Maybe
Microsoft .NET Framework 3.5 AND 4.8.1 on Windows Server 2025 (Server Core installation)	KB5082417	Security Update	2.0.50727.9181 & 3.0.30729.9165 & 4.8.9332.0	Maybe
Microsoft .NET Framework 3.5 AND 4.8.1 on Windows Server 2025	KB5082417	Security Update	2.0.50727.9181 & 3.0.30729.9165 & 4.8.9332.0	Maybe

Security updates (18)

KB5082426 (Security Update)
KB5082424 (Security Update)
KB5082411 (Security Update)
KB5082403 (Security Update)
KB5082404 (Security Update)
KB5082414 (Security Update)
KB5082419 (Security Update)
KB5082413 (Security Update)
KB5082425 (Security Update)
KB5082418 (Security Update)
KB5082420 (Security Update)
KB5082406 (Security Update)
KB5082421 (Security Update)
KB5082427 (Security Update)
KB5082400 (Security Update)
KB5082402 (Security Update)
KB5082417 (Security Update)
KB5082398 (Security Update)

NIST NVD data

NVD status: Analyzed
NVD CVSS: 5.9 (MEDIUM)
NVD weakness: CWE-362
Published to NVD: 14 April 2026
NVD last modified: 6 May 2026

Affected configurations (CPE)

Product	Vulnerable versions
.net framework 3.5	all listed versions
.net framework 4.7.2	all listed versions
.net framework 3.5	all listed versions
.net framework 4.8	all listed versions
.net framework 4.8	all listed versions
.net framework 3.5	all listed versions
.net framework 4.8.1	all listed versions

References

https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-32226 (Vendor Advisory)

Acknowledgments

Anonymous

Revision history

Version	Date	Description
1.0	14 April 2026	Information published.
2.0	11 May 2026	Additional entries have been included in the Security Updates table to include the server versions of .NET Framework. Customers that are running supported version of .NET Framework are encouraged to update to the indicated version to be protected from this vulnerability.