Skype for Business and Microsoft Lync
CVE-2021-26421 — Skype for Business and Lync Spoofing 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:H/PR:L/UI:R/S:C/C:H/I:L/A:N/E:U/RL:O/RC:C
ATTACK VECTOR
Network
ATTACK COMPLEXITY
High
PRIVILEGES REQUIRED
Low
USER INTERACTION
Required
SCOPE
Changed
CONFIDENTIALITY
High
INTEGRITY
Low
AVAILABILITY
None
EXPLOIT CODE MATURITY
Unproven
REMEDIATION LEVEL
Official Fix
REPORT CONFIDENCE
Confirmed
Temporal Score: 5.7
EPSS Score
0.01411
probability of exploitation in the next 30 days
0.69167 percentile - updated 2026-06-21
View on FIRST.org
Affected Products
2 affected products
| Product | KB Article | Severity | Impact | Restart Required |
|---|---|---|---|---|
| Microsoft Lync Server 2013 CU10 | 5003729 (Security Update) |
Important | Spoofing | Maybe |
| Skype for Business Server 2015 CU11 | 5003729 (Security Update) |
Important | Spoofing | Maybe |
Patches
1 patch
| Article | Type | Restart |
|---|---|---|
5003729 |
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
Suresh Chelladurai
References
On This Page