Skype for Business
CVE-2021-24099 — Skype for Business and Lync Denial of Service Vulnerability
Executive Summary
None
Overview
6.5
CVSS MEDIUM
Important
MS Severity
Not Exploited
MS Exploit Status
Less Likely
MS Exploit Likelihood
CVSS Vector
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
ATTACK VECTOR
Network
ATTACK COMPLEXITY
Low
PRIVILEGES REQUIRED
Low
USER INTERACTION
None
SCOPE
Unchanged
CONFIDENTIALITY
None
INTEGRITY
None
AVAILABILITY
High
EXPLOIT CODE MATURITY
Unproven
REMEDIATION LEVEL
Official Fix
REPORT CONFIDENCE
Confirmed
Temporal Score: 5.7
EPSS Score
0.02887
probability of exploitation in the next 30 days
0.85426 percentile - updated 2026-07-25
View on FIRST.org
Affected Products
3 affected products
| Product | KB Article | Severity | Impact | Restart Required |
|---|---|---|---|---|
| Microsoft Lync Server 2013 | 5000675 (Security Update) |
Important | Denial of Service | Maybe |
| Skype for Business Server 2015 CU 8 | 5000675 (Security Update) |
Important | Denial of Service | Maybe |
| Skype for Business Server 2019 CU2 | 5000675 (Security Update) |
Important | Denial of Service | Maybe |
Patches
1 patch
| Article | Type | Restart |
|---|---|---|
5000675 |
Security Update | Maybe |
Known Exploits
No known exploits have been linked for this CVE yet. When available, exploit references will be sourced from public repositories and may be unverified, incomplete, or non-functional. Always review code carefully before use in any environment.
Acknowledgments
Markus Wulftange of Code White GmbH (@codewhitesec)
References
On This Page