CVE-2026-66303
Skype for Business and Lync Denial of Service Vulnerability
Null pointer dereference in Skype for Business allows an authorized attacker to deny service over a network.
Attack profile
How easy it is to exploit
- Attack vector
- Network
- Complexity
- Low
- Privileges needed
- Low
- User interaction
- None
What an attacker can affect
- Confidentiality
- None
- Integrity
- None
- Availability
- High
Exploit likelihood
What each source reports
CVE List Score used
Skype for Business and Lync Denial of Service Vulnerability
Null pointer dereference in Skype for Business allows an authorized attacker to deny service over a network.
- Record
CVE-2026-66303- CVSS 3.1
- 6.5 Medium
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 - Weakness
- CWE-476
- Updated
- 2026-11-02
EUVDEUVD-2026-73940
Null pointer dereference in Skype for Business allows an authorized attacker to deny service over a network.
- Record
EUVD-2026-73940- CVSS 3.1
- 6.5 Medium
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 - Updated
- 2026-11-02
GitHub AdvisoriesGHSA-g37h-5rqx-hvqg
Null pointer dereference in Skype for Business allows an authorized attacker to deny service over...
Null pointer dereference in Skype for Business allows an authorized attacker to deny service over a network.
- Record
GHSA-g37h-5rqx-hvqg- CVSS 3.1
- 6.5 Medium
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H - Weakness
- CWE-476
- Updated
- 2026-11-02
NVD
Null pointer dereference in Skype for Business allows an authorized attacker to deny service over a network.
- Record
CVE-2026-66303- CVSS 3.1
- 6.5 Medium
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H - Weakness
- CWE-476
- Updated
- 2026-11-02
Affected products
History
| Recorded | Changed | Sources |
|---|---|---|
| first indexed | CVE List, EUVD, GitHub Advisories, NVD |
Dates are when Every CVE recorded each change. Upstream dates may differ.
In short
CVE-2026-66303 is a medium vulnerability (CVSS 6.5) in Microsoft Skype For Business Server 2015 Cu13, published September 8, 2026. No source lists public exploit code. EPSS puts the chance of exploitation in the next 30 days at 1.14%, the 66th percentile. No source names a fixed version.