CVE-2026-66303: microsoft skype_for_business_server NULL Pointer Dereference
CVSS: 6.5v3.1MediumAnalyzed
Published 08-09-2026Last modified 14-10-2026
Vulnerability summary
CVE-2026-66303 is a medium (CVSS 6.5) NULL Pointer Dereference vulnerability in microsoft skype_for_business_server. EPSS estimates a 1.14% chance of exploitation in the next 30 days, higher than 66.1% of scored vulnerabilities.
CVSS score
6.5/10
010
Medium · v3.1 (CVE.org)EPSS score
1.14%
0%100%
Low · +0.35 pp in 30 daysKEVNot listedIn no KEV catalog
RansomwareNone recordedNo known use recorded
Public exploits0No public exploits recorded
Timeline
- 08-09-2026PublishedVulnerability first disclosed.
- 14-10-2026Last modifiedVulnerability information updated.
Description
Null pointer dereference in Skype for Business allows an authorized attacker to deny service over a network.
CVSS metrics
2 scores · 2 sources · 1 versionMedium 6.5Preferred score · CVE.org (CNA)
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H/E:U/RL:O/RC:CSourcesAll 2 agree
- NVDNIST6.5MediumCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
EPSS trend
Probability
1.14%
Chance of exploitation in the next 30 days
Percentile
66%
Versus all other CVEs
30-day change
+0.35 pp
From 0.79% on 20-09-2026
20-09-202620-10-2026
EPSS score1.14%
Known exploited
Compare KEV catalogsNot in any of the 3 tracked catalogs.
Public exploits
0 foundNo public exploits indexed.
Weaknesses
CWE · root causeAffected systems
Microsoft5 products
- skype_for_business_server2015:cumulative_update_13 | 2015:cumulative_update_13_hotfix_2 | 2019:cumulative_update_8 | 2019:cumulative_update_8_hotfix1 | 2019:cumulative_update_8_hotfix2
- skype for business server 2015 cu13≥ 9319.0, < 6.0.9319.885
- skype for business server 2019 cu8≥ 2046.0, < 7.0.2046.569
- skype_for_business_server_subscription_edition7.0.2046.849
- skype for business server subscription edition cu1≥ 2046.0, < 7.0.2046.879
1 vendor · 5 products
