CVE-2026-23666
published 2026-04-14CVE-2026-23666: Improper input validation in .NET Framework allows an unauthorized attacker to deny service over a network.
PriorityP349high7.5CVSS 3.1
AVNACLPRNUINSUCNINAH
EPSS
1.33%
67.9th percentile
Improper input validation in .NET Framework allows an unauthorized attacker to deny service over a network.
Affected
13 ranges
| Vendor | Product | Version range | Fixed in |
|---|---|---|---|
| microsoft | microsoft_net_framework_3.5 | >= 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_4.7.2 | >= 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_4.8 | >= 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_4.8.1 | >= 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_4.7.2 | >= 4.7.0 < 4.8.4801.0 | 4.8.4801.0 |
| microsoft | microsoft_net_framework_4.8 | >= 4.8.0 < 4.8.4801.0 | 4.8.4801.0 |
| microsoft | net_framework | — | — |
| microsoft | net_framework | — | — |
| microsoft | net_framework | — | — |
| microsoft | net_framework | — | — |
| microsoft | net_framework | — | — |
| microsoft | net_framework | — | — |
| microsoft | net_framework | — | — |
CVSS provenance
nvdv3.17.5HIGHCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
vendor_redhat7.5HIGH
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GHSA
GHSA-fvc9-q887-5p2h: Concurrent execution using shared resource with improper synchronization ('race condition') in
ghsa_unreviewed·2026-04-14
CVE-2026-23666 [HIGH] CWE-755 GHSA-fvc9-q887-5p2h: Concurrent execution using shared resource with improper synchronization ('race condition') in
Concurrent execution using shared resource with improper synchronization ('race condition') in .NET Framework allows an unauthorized attacker to deny service over a network.
Red Hat
dotnet: .NET Framework: Denial of Service via Race Condition
vendor_redhat·2026-04-14·CVSS 7.5
CVE-2026-23666 [HIGH] CWE-366 dotnet: .NET Framework: Denial of Service via Race Condition
dotnet: .NET Framework: Denial of Service via Race Condition
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.
Statement: Important: A race condition in .NET Framework can lead to a Denial of Service. This flaw allows an unauthenticated attacker to exploit improper synchronization when using shared resources, causing affected systems to become unavailable. This impacts Red Hat Enterprise Linux 8, 9, and 10, as well as Fedora, where .NET is deployed.
Mitigation: Mitigation for this issue is either not available or the currently available options do not m
No detection rules found.
No public exploits indexed.
Bugzilla
CVE-2026-23666 dotnet: .NET Framework: Denial of Service via Race Condition
bugzilla·2026-04-14·CVSS 7.5
CVE-2026-23666 [HIGH] CVE-2026-23666 dotnet: .NET Framework: Denial of Service via Race Condition
CVE-2026-23666 dotnet: .NET Framework: Denial of Service via Race Condition
Concurrent execution using shared resource with improper synchronization ('race condition') in .NET Framework allows an unauthorized attacker to deny service over a network.
Bugzilla
CVE-2026-23666 dotnet10.0: .NET Framework: Denial of Service via Race Condition [fedora-all]
bugzilla·2026-04-14·CVSS 7.5
CVE-2026-23666 [HIGH] CVE-2026-23666 dotnet10.0: .NET Framework: Denial of Service via Race Condition [fedora-all]
CVE-2026-23666 dotnet10.0: .NET Framework: Denial of Service via Race Condition [fedora-all]
Disclaimer: Community trackers are created by Red Hat Product Security team on a best effort basis. Package maintainers are required to ascertain if the flaw indeed affects their package, before starting the update process.
Bugzilla
CVE-2026-23666 dotnet8.0: .NET Framework: Denial of Service via Race Condition [fedora-all]
bugzilla·2026-04-14·CVSS 7.5
CVE-2026-23666 [HIGH] CVE-2026-23666 dotnet8.0: .NET Framework: Denial of Service via Race Condition [fedora-all]
CVE-2026-23666 dotnet8.0: .NET Framework: Denial of Service via Race Condition [fedora-all]
Disclaimer: Community trackers are created by Red Hat Product Security team on a best effort basis. Package maintainers are required to ascertain if the flaw indeed affects their package, before starting the update process.
Bugzilla
CVE-2026-23666 dotnet9.0: .NET Framework: Denial of Service via Race Condition [fedora-all]
bugzilla·2026-04-14·CVSS 7.5
CVE-2026-23666 [HIGH] CVE-2026-23666 dotnet9.0: .NET Framework: Denial of Service via Race Condition [fedora-all]
CVE-2026-23666 dotnet9.0: .NET Framework: Denial of Service via Race Condition [fedora-all]
Disclaimer: Community trackers are created by Red Hat Product Security team on a best effort basis. Package maintainers are required to ascertain if the flaw indeed affects their package, before starting the update process.
Bleepingcomputer
Microsoft April 2026 Patch Tuesday fixes 167 flaws, 2 zero-days
blogs_bleepingcomputer·2026-04-14·CVSS 6.5
[MEDIUM] Microsoft April 2026 Patch Tuesday fixes 167 flaws, 2 zero-days
## Microsoft April 2026 Patch Tuesday fixes 167 flaws, 2 zero-days
## Lawrence Abrams
Today is Microsoft's April 2026 Patch Tuesday with security updates for 167 flaws, including 2 zero-day vulnerabilities.
This Patch Tuesday also addresses eight "Critical" vulnerabilities, 7 of which are remote code execution flaws and the other is a denial of service flaw.
The number of bugs in each vulnerability category is listed below:
93 Elevation of Privilege Vulnerabilities
13 Security Feature Bypass Vulnerabilities
20 Remote Code Execution Vulnerabilities
21 Information Disclosure Vulnerabilities
10 Denial of Service Vulnerabilities
9 Spoofing Vulnerabilities
When BleepingComputer reports on Patch Tuesday security updates, we only count those released by Microsoft today.
Therefore, the
Talos
Microsoft Patch Tuesday for April 2026 - Snort Rule and Prominent Vulnerabilities
blogs_talos·2026-04-14·CVSS 7.5
CVE-2026-23666 [HIGH] Microsoft Patch Tuesday for April 2026 - Snort Rule and Prominent Vulnerabilities
## Microsoft Patch Tuesday for April 2026 - Snort Rule and Prominent Vulnerabilities
Microsoft has released its monthly security update for April 2026, which includes 165 vulnerabilities affecting a wide range of products, including eight Microsoft marked as “critical.”
CVE-2026-23666 is a critical Denial of Service (DoS) vulnerability that affects the .NET framework. Successful exploitation could allow the attacker to deny service over the network.
CVE-2026-32157 is a critical use after free vulnerability in the Remote Desktop Client that results in code execution. Attack requires an authorized user on the client to connect to a malicious server, which could result in code execution on the client.
CVE-2026-32190 is a critical user after free vulnerability in Microsoft Office that can
Qualys
Microsoft and Adobe Patch Tuesday, April 2026 Security Update Review
blogs_qualys·2026-04-14
Microsoft and Adobe Patch Tuesday, April 2026 Security Update Review
## Table of Contents
Microsoft Patch Tuesday forApril2026
Adobe Patches for April2026
Zero-day Vulnerabilities Patched inAprilPatch Tuesday Edition
Critical Severity Vulnerabilities Patched inAprilPatch Tuesday Edition
Other Microsoft Vulnerability Highlights
Microsoft Release Summary
Qualys Monthly Webinar Series
April 2026’s Patch Tuesday arrives with Microsoft addressing a fresh set of vulnerabilities across its ecosystem, reinforcing the ongoing need for timely patching in an increasingly threat-heavy landscape. Here’s a quick breakdown of what you need to know.
## Microsoft Patch Tuesday for April 2026
This month’s release addresses 163 vulnerabilities, including eight critical and 154 important-severity vulnerabilities.
In this month’s updates, Microsoft has addressed one
Sans Isc
Microsoft Patch Tuesday April 2026., (Tue, Apr 14th)
blogs_sans_isc·2026-04-14·CVSS 8.8
[HIGH] Microsoft Patch Tuesday April 2026., (Tue, Apr 14th)
Microsoft Patch Tuesday April 2026.
Published: 2026-04-14. Last Updated: 2026-04-14 17:46:09 UTC
by Johannes Ullrich (Version: 1)
0 comment(s)
This month's Microsoft Patch Tuesday looks like a record one, but let's look at it a bit closer to understand what is happening
The update patches a total of 243 vulnerabilities. However, 78 of them are Chromium issues affecting Microsoft Edge. Patches for Edge were released earlier. This leaves 165 vulnerabilities that are not Edge-related. Of these, 8 are rated critical, and 154 are important. One vulnerability has already been exploited, and another was made public before today but has not yet been seen in the wild.
Noteworthy Vulnerabilities:
CVE-2026-33827 (Windows TCP/IP Remote Code Execution Vulnerability): As a packet nerd, I love thes
Rapid7
Patch Tuesday - April 2026
blogs_rapid7·2026-04-14·CVSS 6.5
[MEDIUM] Patch Tuesday - April 2026
Microsoft is publishing 167 vulnerabilities on April 2026 Patch Tuesday . Microsoft is aware of exploitation in the wild for one of today’s vulnerabilities, and public disclosure for one other. Microsoft evaluates 19 of the vulnerabilities published today as more likely to see future exploitation. So far this month, Microsoft has provided patches to address 80 browser vulnerabilities, which are not included in the Patch Tuesday count above.
## Increasing volumes of vulnerabilities
Regular Patch Tuesday watchers will know that these vulnerability totals are significantly higher than usual, especially the browser numbers. Late last week, Microsoft published patches to resolve more than 60 browser vulnerabilities in a single day, which is a new record in that very specific category.
It mig
Crowdstrike
April 2026 Patch Tuesday: Two Zero-Days and Eight Critical Vulnerabilities Among 164 CVEs
blogs_crowdstrike
April 2026 Patch Tuesday: Two Zero-Days and Eight Critical Vulnerabilities Among 164 CVEs
April 2026 Patch Tuesday: Two Zero-Days and Eight Critical Vulnerabilities Among 164 CVEs Apr 14, 2026
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April 2026 Patch Tuesday: Two Zero-Days and Eight Critical Vulnerabilities Among 164 CVEs Apr 14, 2026
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2026-04-14
Published