EUVD-2026-73941
GHSA-fmx2-865f-8c6j
Severity by source
AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Network-reachable unauthenticated DoS with no auth, no user interaction, and pure availability impact; vendor-provided vector is accurate.
Primary rating from Vendor (microsoft).
CVSS VectorVendor: microsoft
Lifecycle Timeline
7DescriptionCVE.org
Integer underflow (wrap or wraparound) in Skype for Business allows an unauthorized attacker to deny service over a network.
AnalysisAI
Unauthenticated network denial-of-service in Microsoft Skype for Business Server allows a remote attacker to crash the service by triggering an integer underflow (CWE-191) in network-facing processing code. Affected are Skype for Business Server 2015, 2019, and the Subscription Edition across specific cumulative update baselines. …
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Attack ChainAIDerived
Hypothetical attack flow derived from CVE metadata
Vulnerability AssessmentAI
| Exploitation | No special configuration or privileges are required - the vulnerability is reachable by any unauthenticated attacker on the network who can send packets to a Skype for Business Server's network-facing ports. … Additional conditions and limiting factors are described in the full assessment. |
| Risk Assessment | The CVSS 3.1 base score of 7.5 (AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H) accurately reflects network-reachable, unauthenticated service disruption. … Full risk analysis with EPSS, KEV, and SSVC signal comparison available after sign-in. |
| Exploit Scenario | Full exploit scenario with step-by-step reproduction available after sign-in. |
| Remediation | Apply the vendor-released cumulative update patches from Microsoft: upgrade Skype for Business Server 2019 to version 7.0.2046.569 or later, Server 2015 to version 6.0.9319.885 or later, and Subscription Edition to version 7.0.2046.879 or later. … Detailed patch versions, workarounds, and compensating controls in full report. |
Recommended ActionAI
Within 24 hours, inventory all Skype for Business Server instances and verify which versions and cumulative update levels are deployed (2015, 2019, or Subscription Edition). …
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Same weakness CWE-191 – Integer Underflow
View allSame technique Denial Of Service
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External POC / Exploit Code
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