CVE-2021-26877
published 2021-03-11CVE-2021-26877: Windows DNS Server Remote Code Execution Vulnerability
PriorityP270critical9.8CVSS 3.1
AVNACLPRNUINSUCHIHAH
EPSS
16.53%
96.8th percentile
Windows DNS Server Remote Code Execution Vulnerability
Affected
23 ranges
| Vendor | Product | Version range | Fixed in |
|---|---|---|---|
| microsoft | windows_server_2008 | — | — |
| microsoft | windows_server_2008_r2_service_pack_1 | >= 6.1.7601.0 < 6.1.7601.24566 | 6.1.7601.24566 |
| microsoft | windows_server_2008_service_pack_2 | >= 6.0.6003.0 < 6.0.6003.21070 | 6.0.6003.21070 |
| microsoft | windows_server_2012 | — | — |
| microsoft | windows_server_2012 | >= 6.2.9200.0 < 6.2.9200.23298 | 6.2.9200.23298 |
| microsoft | windows_server_2012_r2 | >= 6.3.9600.0 < 6.3.9600.19968 | 6.3.9600.19968 |
| microsoft | windows_server_2016 | — | — |
| microsoft | windows_server_2016 | — | — |
| microsoft | windows_server_2016 | — | — |
| microsoft | windows_server_2016 | >= 10.0.14393.0 < 10.0.14393.4283 | 10.0.14393.4283 |
| microsoft | windows_server_2019 | >= 10.0.17763.0 < 10.0.17763.1817 | 10.0.17763.1817 |
| microsoft | windows_server_version_2004 | >= 10.0.0 < 10.0.19043.867 | 10.0.19043.867 |
| microsoft | windows_server_version_20h2 | >= 10.0.0 < 10.0.19043.867 | 10.0.19043.867 |
| msrc | windows_server_2008_for_32-bit_systems_service_pack_2 | — | — |
| msrc | windows_server_2008_for_x64-based_systems_service_pack_2 | — | — |
| msrc | windows_server_2008_r2_for_x64-based_systems_service_pack_1 | — | — |
| msrc | windows_server_2012 | — | — |
| msrc | windows_server_2012_r2 | — | — |
| msrc | windows_server_2016 | — | — |
| msrc | windows_server_2019 | — | — |
| msrc | windows_server_version_1909 | — | — |
| msrc | windows_server_version_2004 | — | — |
| msrc | windows_server_version_20h2 | — | — |
Detection & IOCsextracted from sources · hover to see the quote
- →Vulnerability is only exploitable if the server is configured to be a DNS server — scope detection/hunting to Windows hosts running the DNS Server role ↗
- →A prerequisite for exploitation is that dynamic updates are enabled on the DNS server — audit DNS zones for dynamic update configuration as a detection/exposure signal ↗
- →Microsoft rates exploitation as 'More Likely' for both latest and older software releases — prioritize alerting on anomalous DNS dynamic update traffic (e.g., malformed or oversized DNS UPDATE packets) to Windows DNS servers ↗
- ·Secure Zone Updates constrains attack sources but does NOT fully prevent exploitation; it should not be treated as a complete mitigation ↗
CVSS provenance
nvdv3.19.8CRITICALCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
nvdv2.07.5HIGHAV:N/AC:L/Au:N/C:P/I:P/A:P
vendor_msrc9.8CRITICAL
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VulDB
Microsoft Windows Server 20H2 up to Server 2016 DNS Server code injection
vuldb·2026-08-20·CVSS 9.8
CVE-2021-26877 [CRITICAL] Microsoft Windows Server 20H2 up to Server 2016 DNS Server code injection
A vulnerability classified as very critical has been found in Microsoft Windows. Affected by this vulnerability is an unknown functionality of the component DNS Server. This manipulation causes code injection.
This vulnerability is registered as CVE-2021-26877. Remote exploitation of the attack is possible. No exploit is available.
To fix this issue, it is recommended to deploy a patch.
GHSA
GHSA-8546-vjcf-9r45: Windows DNS Server Remote Code Execution Vulnerability This CVE ID is unique from CVE-2021-26877, CVE-2021-26894, CVE-2021-26895, CVE-2021-26897
ghsa_unreviewed·2022-05-24·CVSS 9.8
CVE-2021-26893 [CRITICAL] GHSA-8546-vjcf-9r45: Windows DNS Server Remote Code Execution Vulnerability This CVE ID is unique from CVE-2021-26877, CVE-2021-26894, CVE-2021-26895, CVE-2021-26897
Windows DNS Server Remote Code Execution Vulnerability This CVE ID is unique from CVE-2021-26877, CVE-2021-26894, CVE-2021-26895, CVE-2021-26897.
GHSA
GHSA-86v8-8qp7-vj9r: Windows DNS Server Remote Code Execution Vulnerability This CVE ID is unique from CVE-2021-26893, CVE-2021-26894, CVE-2021-26895, CVE-2021-26897
ghsa_unreviewed·2022-05-24·CVSS 9.8
CVE-2021-26877 [CRITICAL] CWE-94 GHSA-86v8-8qp7-vj9r: Windows DNS Server Remote Code Execution Vulnerability This CVE ID is unique from CVE-2021-26893, CVE-2021-26894, CVE-2021-26895, CVE-2021-26897
Windows DNS Server Remote Code Execution Vulnerability This CVE ID is unique from CVE-2021-26893, CVE-2021-26894, CVE-2021-26895, CVE-2021-26897.
GHSA
GHSA-wjv8-g83f-g23g: Windows DNS Server Remote Code Execution Vulnerability This CVE ID is unique from CVE-2021-26877, CVE-2021-26893, CVE-2021-26894, CVE-2021-26897
ghsa_unreviewed·2022-05-24·CVSS 9.8
CVE-2021-26895 [CRITICAL] GHSA-wjv8-g83f-g23g: Windows DNS Server Remote Code Execution Vulnerability This CVE ID is unique from CVE-2021-26877, CVE-2021-26893, CVE-2021-26894, CVE-2021-26897
Windows DNS Server Remote Code Execution Vulnerability This CVE ID is unique from CVE-2021-26877, CVE-2021-26893, CVE-2021-26894, CVE-2021-26897.
GHSA
GHSA-5hxq-rvgg-jqff: Windows DNS Server Remote Code Execution Vulnerability This CVE ID is unique from CVE-2021-26877, CVE-2021-26893, CVE-2021-26894, CVE-2021-26895
ghsa_unreviewed·2022-05-24·CVSS 9.8
CVE-2021-26897 [CRITICAL] GHSA-5hxq-rvgg-jqff: Windows DNS Server Remote Code Execution Vulnerability This CVE ID is unique from CVE-2021-26877, CVE-2021-26893, CVE-2021-26894, CVE-2021-26895
Windows DNS Server Remote Code Execution Vulnerability This CVE ID is unique from CVE-2021-26877, CVE-2021-26893, CVE-2021-26894, CVE-2021-26895.
GHSA
GHSA-96hx-qvj2-8fpm: Windows DNS Server Remote Code Execution Vulnerability This CVE ID is unique from CVE-2021-26877, CVE-2021-26893, CVE-2021-26895, CVE-2021-26897
ghsa_unreviewed·2022-05-24·CVSS 9.8
CVE-2021-26894 [CRITICAL] GHSA-96hx-qvj2-8fpm: Windows DNS Server Remote Code Execution Vulnerability This CVE ID is unique from CVE-2021-26877, CVE-2021-26893, CVE-2021-26895, CVE-2021-26897
Windows DNS Server Remote Code Execution Vulnerability This CVE ID is unique from CVE-2021-26877, CVE-2021-26893, CVE-2021-26895, CVE-2021-26897.
Microsoft
Windows DNS Server Remote Code Execution Vulnerability
vendor_msrc·2021-03-09·CVSS 9.8
CVE-2021-26877 [CRITICAL] Windows DNS Server Remote Code Execution Vulnerability
Windows DNS Server Remote Code Execution Vulnerability
FAQ: Can this vulnerability by mitigated by enabling Secure Zone Updates?
Enabling Secure Zone Updates constrains the potential sources of the attack, but does not completely prevent it. For example, a malicious insider could attack a “secure zone update” DNS server from a domain-joined computer. This is only a partial mitigation.
Does this vulnerability impact just standalone DNS Primary Authoritative Server and not a DNS Server integrated with Active Directory?
This vulnerability impacts any DNS server. The surrounding configuration can limit possible vectors/sources for the attack, but proper mitigation requires this month’s security update patch.
FAQ: If my server is not configured to be a DNS server, it is vulnerable?
No, this v
No detection rules found.
No public exploits indexed.
Trendmicro
March Patch Tuesday: Fixes for Exchange Server, IE
blogs_trendmicro·2021-03-10·CVSS 9.1
[CRITICAL] March Patch Tuesday: Fixes for Exchange Server, IE
# March Patch Tuesday: Fixes for Exchange Server, IE
This month’s Patch Tuesday includes fixes already released for the Microsoft Exchange Server zero-day flaws attributed to Hafnium attacks.
By: Trend Micro
2021/03/10
Read time: ( words)
Save to Folio
This month’s Patch Tuesday features close to a hundred fixes, almost doubling last month’s total. The list includes patches already released for the Microsoft Exchange Server zero-day flaws attributed to Hafnium attacks.
Out of 89 patches released, 14 were rated Critical while the rest were deemed Important. Most of the critical vulnerabilities involve remote code execution (RCE) link except for an information disclosure bug. Fifteen of these were reported by the Zero Day Initiative (ZDI).
Microsoft Exchange Server Vulnerabilities
Th
Tenable
Microsoft’s March 2021 Patch Tuesday Addresses 82 CVEs (CVE-2021-26411)
blogs_tenable·2021-03-09·CVSS 8.8
[HIGH] Microsoft’s March 2021 Patch Tuesday Addresses 82 CVEs (CVE-2021-26411)
## Cloud Exposure
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## Business needs
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Talos
Microsoft Patch Tuesday for March 2021 — Snort rules and prominent vulnerabilities
blogs_talos·2021-03-09·CVSS 8.8
[HIGH] Microsoft Patch Tuesday for March 2021 — Snort rules and prominent vulnerabilities
By Jon Munshaw, with contributions from Nick Biasini.
Microsoft released its monthly security update Tuesday, disclosing 89 vulnerabilities across its suite of products, the most in any month so far this year.
There are 14 critical vulnerabilities as part of this release and one considered of “low” severity. The remainder are all “important.” Three of the critical vulnerabilities are the ones Microsoft disclosed last week in Exchange Server that the company said state-sponsored actors exploited in the wild to steal emails. Microsoft also announced Monday they were releasing patches for older versions of Exchange Server.
All organizations using the affected software should prevent external access to port 443 on Exchange Servers, or set up a VPN to provide external access to port 443. Thi
Talos
Microsoft Patch Tuesday for March 2021 — Snort rules and prominent vulnerabilities
blogs_talos·2021-03-09·CVSS 8.8
[HIGH] Microsoft Patch Tuesday for March 2021 — Snort rules and prominent vulnerabilities
## Microsoft Patch Tuesday for March 2021 — Snort rules and prominent vulnerabilities
By Jon Munshaw, with contributions from Nick Biasini.
Microsoft released its monthly security update Tuesday, disclosing 89 vulnerabilities across its suite of products, the most in any month so far this year.
There are 14 critical vulnerabilities as part of this release and one considered of “low” severity. The remainder are all “important.” Three of the critical vulnerabilities are the ones Microsoft disclosed last week in Exchange Server that the company said state-sponsored actors exploited in the wild to steal emails . Microsoft also announced Monday they were releasing patches for older versions of Exchange Server .
All organizations using the affected software should prevent external access to
Zscaler
Zscaler protects against 7 new vulnerabilities for MS-Window
blogs_zscaler·CVSS 7.0
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Crowdstrike
March 2021 Patch Tuesday: Updates and Analysis
blogs_crowdstrike·CVSS 7.5
CVE-2026-20929 [HIGH] March 2021 Patch Tuesday: Updates and Analysis
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2021-03-11
Published