Microsoft Security Update Guide · Skype for Business
Skype for Business Information Disclosure Vulnerability
Published
What does this mean?
- Information Disclosure. An attacker can see information that is not meant for them.
- It can be exploited over the network (including from the internet if the service is reachable there), without an account and without any user action.
- CVSS 7.5 out of 10: high. Microsoft rates it Important.
- No attacks reported; Microsoft expects exploitation to be less likely.
- What should you do? Install the security update for the version you run (or a later cumulative update):
- Skype for Business Server 2015 CU13: KB5123301
6.0.9319.885 - Skype for Business Server Subscription Edition CU1: KB5123287
7.0.2046.879 - Skype for Business Server 2019 CU8: KB5123300
7.0.2046.569
- Skype for Business Server 2015 CU13: KB5123301
Server-side request forgery (ssrf) in Skype for Business allows an unauthorized attacker to disclose information over a network.
What kind of flaw is this?
- CWE-918: Server-Side Request Forgery (SSRF)
The server can be made to send requests to other systems on the attacker's behalf (server-side request forgery).
Key facts
Released
8 sep 2026
Impact
Information Disclosure
Max severity
Important
Weakness
CVSS 3.1
7.5 / 6.5 (base / temporal)
Vector string
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N/E:U/RL:O/RC:CPublicly disclosed
No
Exploited
No
Exploitability assessment
Exploitation Less Likely
Customer action required
Yes
Links
CVSS metrics
| Base score metrics | |
|---|---|
| Attack Vector | Network |
| Attack Complexity | Low |
| Privileges Required | None |
| User Interaction | None |
| Scope | Unchanged |
| Confidentiality | High |
| Integrity | None |
| Availability | None |
| Temporal score metrics | |
| Exploit Code Maturity | Unproven |
| Remediation Level | Official Fix |
| Report Confidence | Confirmed |
Affected products and updates
| Product | Update | Build |
|---|---|---|
| Skype for Business Server 2015 CU13 | KB5123301 | 6.0.9319.885 |
| Skype for Business Server Subscription Edition CU1 | KB5123287 · Security Update | 7.0.2046.879 |
| Skype for Business Server 2019 CU8 | KB5123300 | 7.0.2046.569 |
FAQ
- How could an attacker exploit this vulnerability?
- An attacker would have to make the service attempt to connect to the malicious server, leading to a Server-side request forgery.
Revisions
| Version | Date | Note |
|---|---|---|
| 1 | 8 sep 2026 | Information published. |
This is in the weekly digest for week 37 · What changed this week? →
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Source: Microsoft Security Update Guide. 365Fanatic is not affiliated with Microsoft.
