VulnerabilityModified

CVE-2021-33779

Windows AD FS Security Feature Bypass Vulnerability

HIGH 8.1EPSS 2.44%

Does this matter?

High impact if exploited, but EPSS currently rates exploitation as unlikely (2.44%). Schedule it in the normal patch cycle and watch for a rise in EPSS or a public exploit.

Description

Windows AD FS Security Feature Bypass Vulnerability

CVSS 3.1: 8.1 HIGHCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:N
EPSS: 2.44% probability · 84th percentile
Public exploits: None in Exploit-DB
CISA KEV: Not listed
Affected: microsoft/windows server 2016 · microsoft/windows server 2019
Source: secure@microsoft.com

EPSS trend

EPSS 2.4% since 26 October 2026; no change recorded yet. Points are recorded when the score first appears and whenever it moves by a percentage point or more.

References

https://msrc.microsoft.com/update-guide/vulnerability/CVE-2021-33779
https://portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2021-33779Patch, Vendor Advisory

Source: NVD record, EPSS from FIRST.org, KEV from CISA, exploits from Exploit-DB. Refreshed daily. Download this record as JSON.