CVE-2021-24099
Skype for Business and Lync Denial of Service Vulnerability
Skype for Business and Lync Denial of Service Vulnerability
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
Skype for Business and Lync Denial of Service Vulnerability
- Record
CVE-2021-24099- 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
EUVDEUVD-2021-11015
Skype for Business and Lync Denial of Service Vulnerability
- Record
EUVD-2021-11015- 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
- 2026-11-03
GitHub AdvisoriesGHSA-gr3f-8f43-4w8g
Skype for Business and Lync Denial of Service Vulnerability
Skype for Business and Lync Denial of Service Vulnerability
- Record
GHSA-gr3f-8f43-4w8g- 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 - Updated
- 2026-11-02
NVD
Skype for Business and Lync Denial of Service Vulnerability
- Record
CVE-2021-24099- 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 - CVSS 2.0
- 4.0 Medium
AV:N/AC:L/Au:S/C:N/I:N/A:P - Updated
- 2026-11-02
Affected products
History
| Recorded | Changed | Sources |
|---|---|---|
| aliases | EUVD | |
| first indexed | CVE List, GitHub Advisories, NVD |
Dates are when Every CVE recorded each change. Upstream dates may differ.
In short
CVE-2021-24099 is a medium vulnerability (CVSS 6.5) in Microsoft Lync Server, published February 25, 2021. No source lists public exploit code. EPSS puts the chance of exploitation in the next 30 days at 3.20%, the 88th percentile. No source names a fixed version.