CVE-2021-26423 | .NET Core and Visual Studio Denial of Service Vulnerability

.NET Core and Visual Studio Denial of Service Vulnerability

Published: 2021-08-12 Last update: 2026-06-16 Assigner: [email protected] Source: [email protected]
NVD Status：Modified，CVE State: published
View at NVD, CVE.org, EUVD

CVE-2021-26423 is rated Moderate Risk (61.2/100): CVSS High severity, with medium exploitation likelihood (EPSS 3.86%). Review affected assets and schedule remediation.

Risk is dynamic; we continuously reassess and refresh what is shown on this page as upstream context changes.

Exploit prediction scoring system (EPSS) score for CVE-2021-26423

EPSS lead: Daily EPSS estimates relative likelihood of exploitation; percentile ranks this CVE among scored vulnerabilities (higher = more severe relative rank).

# Date Old EPSS score New EPSS score Delta (New - Old)
1 2026-06-23 3.74% 3.86% +0.12%
2 2026-06-15 3.37% 3.74% +0.37%
3 2026-04-09 — 3.37% —

Full EPSS history (25 records total)

Common vulnerability scoring system (CVSS) metrics for CVE-2021-26423

CVSS metrics for this CVE.

Base score Version Severity Vector Exploitability Impact Score source
7.5 3.1 HIGH
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H Click to expand
Attack vector (AV:N)
Could be attacked over the internet or any normal routed network—not just someone sitting at the machine.
Attack complexity (AC:L)
Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup.
Privileges required (PR:N)
No account or special rights needed—anonymous or random user is enough.
User interaction (UI:N)
Nobody has to click “OK” or open a trap file; it can work without a victim helping.
Scope (S:U)
Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems.
Confidentiality (C:N)
Doesn’t really leak secrets in a meaningful way.
Integrity (I:N)
Data isn’t meaningfully altered or forged.
Availability (A:H)
Could take the service down hard or make it unusable for people who depend on it.
 3.9 3.6 [email protected]
7.5 3.1 HIGH
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H Click to expand
Attack vector (AV:N)
Could be attacked over the internet or any normal routed network—not just someone sitting at the machine.
Attack complexity (AC:L)
Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup.
Privileges required (PR:N)
No account or special rights needed—anonymous or random user is enough.
User interaction (UI:N)
Nobody has to click “OK” or open a trap file; it can work without a victim helping.
Scope (S:U)
Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems.
Confidentiality (C:N)
Doesn’t really leak secrets in a meaningful way.
Integrity (I:N)
Data isn’t meaningfully altered or forged.
Availability (A:H)
Could take the service down hard or make it unusable for people who depend on it.
 3.9 3.6 [email protected]
5.0 2.0 MEDIUM
AV:N/AC:L/Au:N/C:N/I:N/A:P Click to expand
Access vector (AV:N)
Can be exploited remotely over network reachability.
Access complexity (AC:L)
Exploitation conditions are straightforward and predictable.
Authentication (AU:N)
No authentication is required.
Confidentiality impact (C:N)
No confidentiality impact.
Integrity impact (I:N)
No integrity impact.
Availability impact (A:P)
Partial availability impact.
 10.0 2.9 [email protected]

Weakness enumeration for CVE-2021-26423

GitHub Security Advisory for CVE-2021-26423

GHSA-rh58-r7jh-xhx3 · Severity: high · Ecosystem: nuget — .NET Core Elevation of Privilege Vulnerability

OS Trackers for CVE-2021-26423

vendor priority summary link
redhat high — https://access.redhat.com/security/cve/CVE-2021-26423

Affected software / configurations for CVE-2021-26423

Vendor Product Version Raw CPE
microsoft .net >= 5.0, <= 5.0.8 cpe:2.3:a:microsoft:.net:*:*:*:*:*:*:*:*
microsoft .net_core >= 2.1, <= 2.1.28 cpe:2.3:a:microsoft:.net_core:*:*:*:*:*:*:*:*
microsoft .net_core >= 3.1, <= 3.1.17 cpe:2.3:a:microsoft:.net_core:*:*:*:*:*:*:*:*
microsoft powershell_core >= 7.0, < 7.0.7 cpe:2.3:a:microsoft:powershell_core:*:*:*:*:*:*:*:*
microsoft powershell_core >= 7.1, < 7.1.4 cpe:2.3:a:microsoft:powershell_core:*:*:*:*:*:*:*:*
microsoft visual_studio_2017 >= 15.0, <= 15.9 cpe:2.3:a:microsoft:visual_studio_2017:*:*:*:*:*:*:*:*
microsoft visual_studio_2019 >= 16.0, <= 16.10 cpe:2.3:a:microsoft:visual_studio_2019:*:*:*:*:*:*:*:*
microsoft visual_studio_2019 8.10 cpe:2.3:a:microsoft:visual_studio_2019:8.10:*:*:*:*:macos:*:*

References for CVE-2021-26423

cvelogic Threat Intelligence