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CVE-2018-8340

26
FAUCET Score

CVE-2018-8340 is a security feature bypass vulnerability in Active Directory Federation Services (AD FS) that affects Windows Server 2012 R2 and 2016. It allows an attacker to bypass multi-factor authentication (MFA) due to improper handling of MFA requests. With a CVSS score of 6.5 (Medium), this vulnerability has a low attack complexity and requires low privileges, potentially leading to high confidentiality impact. While there is no known public exploit code or Metasploit modules, the vulnerability has garnered significant community discussion and media coverage, indicating awareness of its potential impact.

Impacted Technologies

VendorProductVersion(s)CPE
r2CPE matchmatch criteria
cpe:2.3:o:microsoft:windows_server_2012:r2:*:*:*:*:*:*:*
Range not provided by sourceCPE matchmatch criteria
cpe:2.3:o:microsoft:windows_server_2016:-:*:*:*:*:*:*:*
1709CPE matchmatch criteria
cpe:2.3:o:microsoft:windows_server_2016:1709:*:*:*:*:*:*:*
1803CPE matchmatch criteria
cpe:2.3:o:microsoft:windows_server_2016:1803:*:*:*:*:*:*:*

CVSS Data

CVSS version used by this source: 3.0

6.5MEDIUM

CVSS:3.0/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N

Attack Vector
NETWORK
Attack Complexity
LOW
Privileges Required
LOW
User Interaction
NONE
Scope
UNCHANGED
Confidentiality Impact
HIGH
Integrity Impact
NONE
Availability Impact
NONE
Exploitability Score
2.8
Impact Score
3.6
CvssVersion
3.0

Exploit Intelligence

EPSS Score
7.58%
Probability of exploitation in next 30 days
EPSS Percentile
93.9%
Percentile rank of EPSS score among Peer Group
As of 2026-07-27
Model: v2026.06.15
This CVE's current EPSS score of 0.0758 is in the 98th percentile among its peer group of 21,958 CVEs.

Social Chatter

The average CVE in this peer group has 0.0 Twitter, 0.0 Reddit, 0.1 Bluesky, 0.0 Mastodon, and 0.1 GitHub mentions.

Media Mentions

The average CVE in this peer group has 0.0 InfoSec Media, 0.0 Vendor Blog, and 0.0 Security Researcher mentions.

Remediation

Patch Available

Vendor Patches (7)

microsoftpatch availablevia nvd_reference
View patch
microsoftpatch availablevia msrc
Product: Windows Server, version 1803 (Server Core Installation)
View patch
microsoftpatch availablevia msrc
Product: Windows Server, version 1709 (Server Core Installation)
View patch
microsoftpatch availablevia msrc
Product: Windows Server 2016
View patch
microsoftpatch availablevia msrc
Product: Windows Server 2016 (Server Core installation)
View patch
microsoftpatch availablevia msrc
Product: Windows Server 2012 R2
View patch
microsoftpatch availablevia msrc
Product: Windows Server 2012 R2 (Server Core installation)
View patch

Vendor Advisories (1)

microsoft2018-Aug/CVE-2018-8340Important

ADFS Security Feature Bypass Vulnerability

Aug 14, 2018

References

portal.msrc.microsoft.com / en-US/security-guidance/advisory/CVE-2018-8340
PatchVendor Advisory
securityfocus.com / bid/105029
Third Party AdvisoryVDB Entry
securitytracker.com / id/1041474
Third Party AdvisoryVDB Entry