CVE-2026-66303 json
Skype for Business and Lync Denial of Service Vulnerability
published 2026-09-08 2 mo ago modified 2026-10-31 8 d ago also EUVD-2026-73940
- cvss
- 6.5
- version 3.1, CNA
- cisa kev
- Not listed
- not in CISA's catalog
- epss
- 1.1%
- EPSS 1.1% chance of exploitation in 30 days, percentile 66%
- public exploits
- 0
- none known
Summary
Null pointer dereference in Skype for Business allows an authorized attacker to deny service over a network.
Patch / fix
- Microsoft Skype for Business Server 2015 CU13 6.0.9319.885
- Microsoft Skype for Business Server 2019 CU8 7.0.2046.569
- Microsoft Skype for Business Server Subscription Edition CU1 7.0.2046.879
CISA SSVC
- Exploitation
- none
- Automatable
- no
- Technical impact
- partial
- Assessed
- 2 mo ago
Exploit prediction
1.14% chance of exploitation in the next 30 days, higher than 66% of all scored CVEs (FIRST EPSS, 2026-11-08).
CVSS scores
| assigned by | version | score | vector |
|---|---|---|---|
| CNA | 3.1 | 6.5 | CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H/E:U/RL:O/RC:C |
| CNA | 3.1 | 6.5 | CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H |
Affected products
- Microsoft Skype for Business Server 2015 CU13
- Microsoft Skype for Business Server 2019 CU8
- Microsoft Skype for Business Server Subscription Edition CU1
Classification
- Weakness
-
- CWE-476 NULL Pointer Dereference
References
-
msrc.microsoft.com
/update-guide/vulnerability/CVE-2026-66303
vendor-advisory, patch
Sources
- CVE List CVE-2026-66303
- NVD CVE-2026-66303
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