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CVE-2026-69646Important

Skype for Business Spoofing Vulnerability

MSRC advisory NVD CVE.org

Assessment

Improper verification of cryptographic signature in Skype for Business allows an unauthorized attacker to perform spoofing over an adjacent network.

Severity
Important
CVSS base score
8.3CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:L/E:U/RL:O/RC:C
Impact
Spoofing
EPSS, next 30 days
0.3%Higher than 22.5% of scored CVEs · FIRST model run 26 Sep 2026 · about EPSS
Exploitability
Exploitation Less Likely
Publicly disclosed
No
Customer action
Required: apply the update
Component
Skype for Business
Weakness
CWE-347: Improper Verification of Cryptographic Signature
Issued by
Microsoft
Published
8 Sep 2026 · September 2026
Last revised
8 Sep 2026

Updates that fix it

3 KBs
KBTypeRestartApplies toOther CVEs
KB5123287 Security Update — Skype for Business Server Subscription Edition CU1 All CVEs in KB5123287
KB5123300 Security Update — Skype for Business Server 2019 CU8 All CVEs in KB5123300
KB5123301 Security Update — Skype for Business Server 2015 CU13 All CVEs in KB5123301

Affected products

Microsoft Office
3 affected products
  • Skype for Business Server 2015 CU13
  • Skype for Business Server 2019 CU8
  • Skype for Business Server Subscription Edition CU1
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