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CVE-2021-26701

📛 CVE Title

Arch Linux: Arbitrary code execution (CVE-2021-26701)

⬇ Download JSON

Description

A remote code execution vulnerability exists in .NET 5.0 before Runtime 5.0.4 and SDK 5.0.104 as well as .NET Core 3.1 before Runtime 3.1.13 and SDK 3.1.113 due to how text encoding is performed in the System.Text.Encodings.Web package, caused by a buffer overrun.

Description (MITRE) cveawg.mitre.org

Pulled from cveawg.mitre.org/api/cve/CVE-2021-26701 on 2026-06-30. Shown when MITRE's text differs from the cvelistV5 mirror.

.NET Core Remote Code Execution Vulnerability

Overview

State
—
Assigner (CNA)
—
CVSS severity
MEDIUM
CVSS score
CVSS 5.0 / 10 5.0 5.0 / 10
CVSS vector
AV:N/AC:L/Au:N/C:P/I:P/A:P
Effective score
5.0 / 10 MEDIUM source: CNA overview
MSRC score
8.1 / 10 HIGH MS rating: Critical · Remote Code Execution
CWE(s)
—
Reserved
—
Published
2021-02-25 00:00 UTC
Last updated
2026-02-19 01:09 UTC
Source
https://www.rapid7.com/db/vulnerabilities/arch-linux-cve-2021-26701/

NVD triage scoring NVD CVE 2.0

Layer NVD adds on top of the CNA's CVE record — published / last-modified timestamps, exploitability / impact subscores, and the FIRST.org EPSS probability that this CVE will be exploited in the wild in the next 30 days.

NVD published
2021-02-25 23:15:16 UTC
NVD last modified
2024-11-21 05:56:41 UTC
NVD CVSS v3.1
CVSS 8.1 / 10 8.1 8.1 / 10 HIGH source: secure@microsoft.com
NVD CVSS vector
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H
Exploitability subscore
2.2 / 10
Impact subscore
5.9 / 10
EPSS score
0.0277 (probability of exploitation in next 30 days)
EPSS percentile
86.24% vs all CVEs — higher = more likely to be exploited, as of 2026-05-27

NVD / KEV / EPSS data refreshed 2026-05-28 03:18 UTC. Re-run the 🛰 Backfill from NVD button above to refresh.

European Union Vulnerability Database ENISA EUVD

ENISA's official EU repository for curated vulnerability intelligence. Carries a separate identifier (EUVD-YYYY-NNNN) and frequently exposes an earlier-published description + CVSS than NVD does.

EUVD ID
EUVD-2021-0826
Assigner
microsoft
Published
Feb 25, 2021, 11:02:00 PM
Updated
May 28, 2026, 7:31:26 PM
EUVD base score (CVSS 3.1)
8.1 / 10
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H/E:U/RL:O/RC:C
EUVD-reported EPSS
30.3200
Vendors
Microsoft
Products
Microsoft Visual Studio 2019 version 16.7 (includes 16.0 – 16.6) (16.0.0 <publication)
.NET 5.0 (5.0.0 <publication)
Visual Studio 2019 for Mac (8.0.0 <publication)
PowerShell Core 7.1 (7.1.0 <publication)
Microsoft Visual Studio 2019 version 16.8 (includes 16.0 - 16.7) (16.0 <publication)
Microsoft Visual Studio 2019 version 16.4 (includes 16.0 - 16.3) (16.0 <publication)
.NET Core 2.1 (2.1 <publication)
Microsoft Visual Studio 2017 version 15.9 (includes 15.0 - 15.8) (15.9.0 <publication)
PowerShell Core 7.0 (7.0.0 <publication)
.NET Core 3.1 (3.1 <publication)
Microsoft Visual Studio 2019 version 16.9 (includes 16.0 - 16.8) (15.0.0 <publication)
Aliases
GHSA-ghhp-997w-qr28

ENISA description: .NET Core Remote Code Execution Vulnerability

EUVD references (7)

Microsoft Security Response Center MSRC

Microsoft's vendor-authoritative record from the Security Update Guide — its own CVSS score, impact, severity rating, exploit assessment, and KB-article fixes. Refreshed 2026-08-11 01:47 UTC (source: CVRF).

MS severity
Critical
Impact
Remote Code Execution
MS CVSS base score
8.1 / 10 (temporal 7.1)
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H/E:U/RL:O/RC:C
Exploit assessment
Publicly Disclosed:Yes;Exploited:No;Latest Software Release:Exploitation Less Likely;Older Software Release:Exploitation Less Likely;DOS:N/A
Release
2021-Feb
Microsoft remediations / KB articles (9)
Microsoft FAQ (1)

Is Visual Studio affected by this vulnerability?

Visual Studio contains the binaries for .NET, but Visual Studio is not vulnerable to this issue. The update is offered to include the .NET files so any future applications built in Visual Studio which include .NET functionality will be protected from this issue.

Affected products — CPE 2.3 (9) NVD

NVD's normalized CPE 2.3 matchers, used by vendor tools (vulnerability scanners, asset managers) for automated detection. Compare with the CNA's free-text "Affected products" section above.

  • cpe:2.3:a:microsoft:.net:*:*:*:*:*:*:*:*
  • cpe:2.3:a:microsoft:.net_core:*:*:*:*:*:*:*:*
  • cpe:2.3:a:microsoft:powershell_core:7.0:*:*:*:*:*:*:*
  • cpe:2.3:a:microsoft:powershell_core:7.1:*:*:*:*:*:*:*
  • cpe:2.3:a:microsoft:visual_studio_2019:*:*:*:*:*:*:*:*
  • cpe:2.3:a:microsoft:visual_studio_2019:-:*:*:*:*:macos:*:*
  • cpe:2.3:o:fedoraproject:fedora:32:*:*:*:*:*:*:*
  • cpe:2.3:o:fedoraproject:fedora:33:*:*:*:*:*:*:*
  • cpe:2.3:o:fedoraproject:fedora:34:*:*:*:*:*:*:*

Vendor references (0)

References embedded in the original CVE record by the assigning CNA.

None in the CVE record.

MITRE references (7) cveawg.mitre.org

Pulled from MITRE's CVE Services API by the 🛰 Backfill from MITRE button.

Web references (16)

DuckDuckGo results ranked by threat-intel / vendor advisory domains. Generated by the 🔎 Find references (web) button above — same flow as the Remediations search.

NVD-tagged references (14)

Reference list NVD curates from the CNA record, vendor advisories, and third-party reports. The tag chips below are NVD's analyst-assigned categories.

Remediations (10)

  • Update Software, Mitigation M1051 - Enterprise | MITRE ATT&CK®
    web:attack.mitre.org

    This mitigation can be implemented through the following measures: Regular Operating System Updates Implementation: Apply the latest Windows security updates monthly using WSUS (Windows Server Update Services) or a similar patch management solution. Configure systems to check for updates automatically and schedule reboots during maintenance ...

    2026-05-28 05:18 UTC
  • Mitigate RedSun Zero-Day Without A Patch | Qualys
    web:blog.qualys.com

    Key Takeaways RedSun is a critical zero-day vulnerability in Microsoft Defender that allows low-privileged users to gain SYSTEM access No patch is currently available, leaving all Defender-enabled Windows systems potentially exposed Qualys VMDR detects affected assets instantly (QID 92382) TruRisk™ Eliminate enables immediate mitigation , removing exploitability without waiting for a fix ...

    2026-05-28 05:18 UTC
  • Microsoft Patch Tuesday March 2026 - 78 Vulnerabilities Fixed ...
    web:cybersecuritynews.com

    Microsoft released its March 2026 Patch Tuesday security update on March 10, 2026, addressing 78 vulnerabilities across Windows, Microsoft Office, Azure, SQL Server, and .NET. The update includes one actively exploited zero-day vulnerability and multiple Critical-rated flaws demanding immediate attention from security teams. The most urgent fix this month is CVE -2026-21262, the sole zero-day ...

    2026-05-28 05:18 UTC
  • Security Update Guide - Microsoft
    web:msrc.microsoft.com

    The Microsoft Security Response Center (MSRC) investigates all reports of security vulnerabilities affecting Microsoft products and services, and provides the information here as part of the ongoing effort to help you manage security risks and help keep your systems protected.

    2026-05-28 05:18 UTC
  • Patch Tuesday Vulnerability Insights - Action1
    web:www.action1.com

    This Patch Tuesday brings 55 vulnerability fixes from Microsoft, including six zero-days. Third-party overview includes actively exploited vulnerabilities in web browsers, Cisco, Fortinet, ServiceNow, Palo Alto, SAP, WordPress, Adobe, Oracle, and many more.

    2026-05-28 05:18 UTC
  • Microsoft KB Catalog: Updates, Issues, & Feedback - NinjaOne
    web:www.ninjaone.com

    Catalog of Microsoft KB updates with insights on performance & user sentiment. Find out what's working, what's not, & make informed decisions.

    2026-05-28 05:18 UTC
  • Oracle Critical Patch Update Advisory - April 2026
    web:www.oracle.com

    This Critical Patch Update contains 481 new security patches across the product families listed below. Please note that an MOS note summarizing the content of this Critical Patch Update and other Oracle Software Security Assurance activities is located at April 2026 Critical Patch Update: Executive Summary and Analysis.

    2026-05-28 05:18 UTC
  • Microsoft fixes 167 security flaws in April, second biggest Patch ...
    web:www.pcworld.com

    This month's Patch Tuesday includes an actively exploited Office zero-day vulnerability and several critical RCE bugs in Windows and Remote Desktop.

    2026-05-28 05:18 UTC
  • Windows 11 April 2026 Update tested: What's new, improved and fixed
    web:www.windowslatest.com

    Windows 11 April 2026 update adds Narrator Copilot support, faster Settings, File Explorer fixes, and key security improvements.

    2026-05-28 05:18 UTC
  • Patch Tuesday May 2026: Security Updates & CVE Analysis
    web:zecurit.com

    Get the complete breakdown of Microsoft's May 2026 Patch Tuesday. We analyze the latest security updates and all critical CVEs .

    2026-05-28 05:18 UTC

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Raw JSON

The full cvelistV5 record. Download as CVE-2021-26701.json.

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