EUVD-2026-43996
GHSA-gcv2-qw2g-r29w
Severity by source
AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Remotely reachable AD FS listener needs no auth or interaction (AV:N/AC:L/PR:N/UI:N); a stack overflow crashes the service, so availability-only impact (A:H, C:N/I:N).
Primary rating from Vendor (microsoft).
CVSS VectorVendor: microsoft
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Lifecycle Timeline
2DescriptionCVE.org
Stack-based buffer overflow in Active Directory Federation Services allows an unauthorized attacker to deny service over a network.
AnalysisAI
Denial of service in Microsoft Active Directory Federation Services (AD FS) allows a remote, unauthenticated attacker to crash the service by triggering a stack-based buffer overflow over the network (CVSS 7.5, availability-only impact). Because AD FS brokers single sign-on and federated authentication, a successful attack can knock out login for every downstream application that relies on it. …
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Attack ChainAIDerived
Hypothetical attack flow derived from CVE metadata
Vulnerability AssessmentAI
| Exploitation | Exploitation requires network reachability to a running AD FS service endpoint; the attacker needs no authentication, no privileges, and no user interaction (AV:N/PR:N/UI:N/AC:L), so any host able to reach the AD FS or Web Application Proxy listener can attempt it against default configurations. … Additional conditions and limiting factors are described in the full assessment. |
| Risk Assessment | The CVSS 3.1 vector (AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H, base 7.5) describes an attractive, low-friction DoS: reachable over the network, low attack complexity, no privileges, and no user interaction - but the impact is strictly availability, with no confidentiality or integrity loss. … Full risk analysis with EPSS, KEV, and SSVC signal comparison available after sign-in. |
| Exploit Scenario | A remote attacker with no credentials sends a crafted request to an internet-reachable AD FS endpoint, overflowing a fixed-size stack buffer and crashing the service. With AD FS down, users and applications relying on it for single sign-on can no longer authenticate, producing an outage across all federated services. … |
| Remediation | Apply the Microsoft security update for CVE-2026-50695 as delivered through the monthly cumulative update for each affected Windows Server version; Patch available per vendor advisory (an exact fixed build number is not specified in the provided data, so obtain the precise KB from the MSRC update guide at https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-50695). … Detailed patch versions, workarounds, and compensating controls in full report. |
Recommended ActionAI
Within 24 hours, inventory all Microsoft AD FS servers in the environment and verify their network accessibility to untrusted networks. …
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External POC / Exploit Code
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