CVE-2021-40456 json
Windows AD FS Security Feature Bypass Vulnerability
published 2021-10-13 5 y ago modified 2026-06-17 4 mo ago also EUVD-2021-27633
- cvss
- 7.5
- version 3.1, CNA
- cisa kev
- Not listed
- not in CISA's catalog
- epss
- 2.3%
- EPSS 2.3% chance of exploitation in 30 days, percentile 83%
- public exploits
- 0
- none known
Summary
Windows AD FS Security Feature Bypass Vulnerability
Patch / fix
- Microsoft Windows Server 2019 10.0.17763.2237
- Microsoft Windows Server 2019 (Server Core installation) 10.0.17763.2237
- Microsoft Windows Server 2022 10.0.20348.288
- Microsoft Windows Server version 2004 10.0.19041.1288
- Microsoft Windows Server version 20H2 10.0.19042.1288
CISA SSVC
- Exploitation
- none
- Automatable
- yes
- Technical impact
- partial
- Assessed
- 2 y ago
Exploit prediction
2.34% chance of exploitation in the next 30 days, higher than 83% of all scored CVEs (FIRST EPSS, 2026-11-08).
CVSS scores
| assigned by | version | score | vector |
|---|---|---|---|
| CNA | 3.1 | 5.3 | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N/E:U/RL:O/RC:C |
| CNA | 3.1 | 5.3 | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N |
| CNA | 3.1 | 7.5 | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N |
| NVD | 2.0 | 5.0 | AV:N/AC:L/Au:N/C:P/I:N/A:N |
Affected products
- Microsoft Windows Server 2019
- Microsoft Windows Server 2019 (Server Core installation)
- Microsoft Windows Server 2022
- Microsoft Windows Server version 2004
- Microsoft Windows Server version 20H2
Classification
- Weakness
-
- CWE-863 Incorrect Authorization
References
-
portal.msrc.microsoft.com
/en-US/security-guidance/advisory/CVE-2021-40456
patch, vendor-advisory
Sources
- CVE List CVE-2021-40456
- NVD CVE-2021-40456
Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.