CVE-2021-26421 is a spoofing vulnerability affecting Microsoft Skype for Business and Lync Server. With a CVSS score of 7.1 (HIGH), it presents a significant risk, requiring user interaction but allowing an unauthenticated attacker to achieve high confidentiality impact and low integrity impact over a network. Despite its severity, there is no known active exploitation, public exploit code (Metasploit, Nuclei, ExploitDB), or inclusion in CISA's KEV catalog, though it garnered some community discussion and media coverage during its disclosure.
| Vendor | Product | Version(s) | CPE |
|---|---|---|---|
2013CPE matchmatch criteria | cpe:2.3:a:microsoft:lync_server:2013:cumulative_update_10:*:*:*:*:*:* | ||
2015CPE matchmatch criteria | cpe:2.3:a:microsoft:skype_for_business_server:2015:cumulative_update_11:*:*:*:*:*:* |
CVSS version used by this source: 3.1
CVSS:3.1/AV:N/AC:H/PR:L/UI:R/S:C/C:H/I:L/A:N
The average CVE in this peer group has 0.0 Twitter, 0.1 Reddit, 0.2 Bluesky, 0.1 Mastodon, and 0.2 GitHub mentions.
The average CVE in this peer group has 0.3 InfoSec Media, 0.0 Vendor Blog, and 0.1 Security Researcher mentions.