CVE-2026-69646

Unauthenticated spoofing via improper signature verification

Published Sep 8, 2026 · Updated Sep 10, 2026

Improper signature verification in Microsoft Skype for Business Server allows remote attackers to spoof trusted data over an adjacent network. Microsoft has not disclosed the affected message or verifier beyond stating that cryptographic signatures are improperly verified. No authentication or user interaction is required, and successful spoofing can expose or alter data and interrupt service.

CVSS severity8.3
High
EPSS probability0.21%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
Coverage for this vulnerability

See if you're affected

Explore vulnerability checks for your environment with Hinoki.

Book a demo

Summary

What happened

Improper signature verification in Microsoft Skype for Business Server allows remote attackers to spoof trusted data over an adjacent network. Microsoft has not disclosed the affected message or verifier beyond stating that cryptographic signatures are improperly verified. No authentication or user interaction is required, and successful spoofing can expose or alter data and interrupt service.

The record

CVE
CVE-2026-69646
Published
Sep 8, 2026
Updated
Sep 10, 2026
Vendor
Microsoft
Product
Skype for Business Server Subscription Edition
Classifications
CWE-347
Attack vector
adjacent
Privileges
unauthenticated

Timeline

How it unfolded

  1. Sep 8, 2026CVE publishedPublication date reported by the CVE source.
  2. Sep 10, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

Compare your product and version with the public record. A matching version still requires validation against your environment.

Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=2046.0 <7.0.2046.879

What conditions does exploitation require?

Attack vectoradjacent
Required privilegesunauthenticated

What is affected?

Microsoft · Skype for Business Server Subscription Editionversion=2046.0 <7.0.2046.879
Microsoft · Skype for Business Serverversion=2046.0 <7.0.2046.569; version=9319.0 <6.0.9319.885

Published CVSS scores

8.3MicrosoftCVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:L

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 9, 2026Sep 15, 2026
Latest reporting daySep 15, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectoradjacent
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-347Improper Verification of Cryptographic Signature

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

See the directory against your own environment.

Your stack

Check the software in your environment

Book a demo to see how Hinoki identifies affected software and validates exploitability in your environment.

Book a demo