Microsoft Security Update Guide · Copilot
Microsoft 365 Copilot's Business Chat Elevation of Privilege Vulnerability
Published
What does this mean?
- Elevation of Privilege. An attacker can gain more rights than they should have, for example admin rights.
- It can be exploited over the network (including from the internet if the service is reachable there), without an account and if a user takes part, for example by opening a link or file.
- CVSS 8.8 out of 10: high. Microsoft rates it Critical.
- What should you do? Nothing: Microsoft fixed this in the cloud service. There is no update to install.
Url redirection to untrusted site ('open redirect') in Microsoft 365 Copilot's Business Chat allows an unauthorized attacker to elevate privileges over a network.
What kind of flaw is this?
- CWE-601: URL Redirection to Untrusted Site ('Open Redirect')
A link on a trusted site can send visitors on to an attacker's site (open redirect).
Key facts
Released
18 jun 2026
Impact
Elevation of Privilege
Max severity
Critical
Weakness
CVSS 3.1
8.8 / 7.7 (base / temporal)
Vector string
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H/E:U/RL:O/RC:CPublicly disclosed
No
Exploited
No
Exploitability assessment
N/A
Customer action required
No, fixed by Microsoft
Links
CVSS metrics
| Base score metrics | |
|---|---|
| Attack Vector | Network |
| Attack Complexity | Low |
| Privileges Required | None |
| User Interaction | Required |
| Scope | Unchanged |
| Confidentiality | High |
| Integrity | High |
| Availability | High |
| Temporal score metrics | |
| Exploit Code Maturity | Unproven |
| Remediation Level | Official Fix |
| Report Confidence | Confirmed |
Affected products and updates
| Product | Update | Build |
|---|---|---|
| Microsoft 365 Copilot | — | — |
FAQ
- Why are there no links to an update or instructions with steps that must be taken to protect from this vulnerability?
- This vulnerability has already been fully mitigated by Microsoft. There is no action for users of this service to take. The purpose of this CVE is to provide further transparency. Please see Toward greater transparency: Unveiling Cloud Service CVEs for more information.
Revisions
| Version | Date | Note |
|---|---|---|
| 1 | 18 jun 2026 | Information published. |
What changed in Microsoft 365 this week? →
View at Microsoft → ← All security advisories
Source: Microsoft Security Update Guide. 365Fanatic is not affiliated with Microsoft.
