Security Digest · Vulnerability record · Known exploited
CVE-2023-41763: Microsoft Skype for Business Privilege Escalation Vulnerability
Exploited in the wild (CISA KEV). Skype for Business Elevation of Privilege Vulnerability
CISA KEV · added 2023-10-10 CVSS 5.3 Medium EPSS 90.5% · p99.8
Should you act?
Exploited: patch now if you run it
CISA has confirmed exploitation in the wild. This signal is computed from CISA KEV, EPSS and CVSS data; it is not an editorial verdict.
- Yes, if you run Microsoft Skype for Business. CISA added this CVE to its Known Exploited Vulnerabilities catalog on 2023-10-10, which means there is reliable evidence of exploitation in the wild. US federal agencies must remediate by 2023-10-31; treat that as the outer limit, not the target.
- EPSS 90.5%, percentile 99.8: FIRST’s model estimates a 90.5% chance of exploitation activity in the next 30 days, higher than 99.8% of all scored CVEs (very high). EPSS is a probability, not a verdict.
- Remotely reachable with no login and no user interaction. If the vulnerable service is exposed to the internet, prioritize it.
What it is
Skype for Business Elevation of Privilege Vulnerability
CISA’s summary
Microsoft Skype for Business contains an unspecified vulnerability that allows for privilege escalation.
Weakness type: CWE-918.
Product: Microsoft Skype for Business · Assigned by: microsoft · Published: 2023-10-10
Affected and fixed versions
| Vendor | Product | Affected versions (per CVE record) |
|---|---|---|
| Microsoft | Skype for Business Server 2015 CU13 | 9319.0 < 6.0.9319.869 |
| Microsoft | Skype for Business Server 2019 CU7 | 2046.0 < 7.0.246.530 |
Severity scores
| Scored by | CVSS | Score | Vector |
|---|---|---|---|
| microsoft | 3.1 | 5.3 Medium | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N/E:P/RL:O/RC:C |
- Attack vector: network (remotely reachable)
- Attack complexity: low
- Privileges required: none (no login)
- User interaction: none
- Scope: unchanged
CVSS measures how bad a flaw is if exploited, not how likely exploitation is. Read it next to the exploitation data below.
Exploitation and urgency
- CISA KEV: added 2023-10-10; federal due date 2023-10-31. Known ransomware use: Unknown.
- CISA required action: Apply mitigations per vendor instructions or discontinue use of the product if mitigations are unavailable.
- CISA SSVC assessment: exploitation active, automatable yes, technical impact partial.
- FIRST EPSS (model of 2026-10-21): 90.55% probability of exploitation activity in the next 30 days; percentile 99.8.
Timeline
- — Added to CISA’s Known Exploited Vulnerabilities catalog
- — CVE record published by microsoft
- — CISA remediation deadline for US federal agencies
- — CVE record last updated
Sources and references
Original sources first. Version and fix details should always be confirmed against the vendor or project advisory.
Vendor and project advisories, patches
- Skype for Business Elevation of Privilege Vulnerability msrc.microsoft.com
- Listed in CISA KEV notes (msrc.microsoft.com) msrc.microsoft.com
Vulnerability records
- CVE.org record CVE-2023-41763 cve.org
- NVD entry CVE-2023-41763 nvd.nist.gov
Government
All exploited Microsoft vulnerabilities · Today’s Security Digest