Exploited

CVE-2020-1350

Microsoft Windows DNS Server Remote Code Execution Vulnerability

At a glance

Exploited. Added to CISA’s catalog of exploited vulnerabilities on November 3, 2021.

Affected product: Microsoft Windows (category Operating systems, indicative classification). Name in CISA’s catalog: Microsoft Windows.

What should I do?

Apply the security update from Microsoft.

Deadline set by CISA for US federal agencies: 181 days (due May 3, 2022). It only binds those agencies, but it is a useful measure of urgency.

CVE-2020-1350 in Microsoft’s Security Update Guide
Microsoft security advisories page (general page, not the advisory for this vulnerability)
The vendor’s specific advisory is listed in the NVD references: CVE-2020-1350 on the NVD website.

Original text of the required action (CISA)

Apply updates per vendor instructions.

Timeline

July 14, 2020 Vulnerability published Publication date (NVD)
November 3, 2021 Exploitation confirmed Added to CISA’s KEV catalog
May 3, 2022 CISA deadline Remediation deadline set for US federal agencies

The facts, with their sources

Exploitation confirmed: Yes, on November 3, 2021 Date added to the catalog of exploited vulnerabilities. Exploitation itself may have started earlier. Source: KEV catalog, collected September 29, 2026 at 14:57 UTC
Ransomware: No known use to date That does not guarantee it is not being used: the information is not public. Source: KEV catalog, collected September 29, 2026 at 14:57 UTC
Hunt for compromise: Not requested by CISA Source: KEV catalog, collected September 29, 2026 at 14:57 UTC
CISA required action: Apply the security update from Microsoft. Rewritten by this site from CISA’s original text. Source: KEV catalog, collected September 29, 2026 at 14:57 UTC
CISA deadline: May 3, 2022, 181 days Set for US federal agencies: a measure of urgency, not an obligation elsewhere. Source: KEV catalog, collected September 29, 2026 at 14:57 UTC
Microsoft patch: Not available Source: Security Update Guide, collected September 29, 2026 at 14:57 UTC
Vulnerability published: July 14, 2020 Source: National Vulnerability Database (NVD), collected September 29, 2026 at 15:00 UTC
Product according to CISA: Microsoft Windows Filed by this site under “Operating systems” (indicative classification). Source: KEV catalog, collected September 29, 2026 at 14:57 UTC
CVSS vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H Technical detail of the score: attack vector, complexity, impact. Source: National Vulnerability Database (NVD), collected September 29, 2026 at 15:00 UTC

Severity and activity

10.0 / 10 CVSS severity: critical

Score from the NVD. Collected Sep 29, 2026.

— Probability of exploitation in the next 30 days (EPSS)

FIRST’s EPSS model. Since exploitation is already confirmed, this figure is mostly useful to compare activity. Collected Sep 29, 2026.

Description

A remote code execution vulnerability exists in Windows Domain Name System servers when they fail to properly handle requests, aka 'Windows DNS Server Remote Code Execution Vulnerability'.

Microsoft Windows DNS Servers fail to properly handle requests, allowing an attacker to perform remote code execution in the context of the Local System Account. The vulnerability is also known under the moniker of SIGRed.

Summary from CISA (KEV catalog).

CERT-FR advisories

No advisory among the latest CERT-FR publications this site follows. That does not mean there are none.

Information reused under the Open Licence 2.0 (Etalab); the date of last update is shown for each advisory. This site is neither affiliated with nor endorsed by ANSSI.

Sources for this page

CISA KEV catalog: exploitation, date added, required action, deadline, ransomware.
Microsoft Security Update Guide: product, patch.
NVD (NIST): CVSS severity, publication date, description, vendor references.
EPSS (FIRST): probability of exploitation.
CERT-FR: advisories and alerts (in French).
Brand and category: indicative classification by this site (method).